mech73
L plate rider.
Posts: 45
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Post by mech73 on Aug 26, 2016 11:36:21 GMT 1
Hi, New on here, so hope its ok to start with questions. I have just bought a 350 F2 although it's been changed to look like an N2. It doesn't go quite right, so any pointer would be useful. As bought it didn't seem to have any engine issues apart from running obviously rich which seemed to be at most throttle positions and revs, although it's slightly better with a wide open throttle and when accelerating. As far as I know the motor is completely standard and has no mods. Is running the original exhausts and air box. It's got 3800 miles on the clock which may be genuine although I can't be certain. First thing I did was check the carbs and air filter. The air filter had disintegrated and most of it was in bit's spread around the air box. The carb components look almost like new with no visible wear and all the sizes, clip positions and numbers what they should be for an F2 (although I didn't find or check the power jets). Choke valve was in good condition and seems to seal ok. There didn't seem to be any bits of air filter in the carbs, but I expect some bits have gone through into the motor. Float heights were ~21mm and 20.5mm. I set them both to 21mm. On re-assembly with a new filter there was no difference at all in the running. If I turn the fuel tap off it does clear and run better briefly before running out of fuel. I've now dropped the needle one clip position, which put the clip in the top groove. This has made a significant improvement. Unscrewing the air screw out to 3 turns (beyond there it made no difference) improved the tickover. On acceleration it now runs farly cleanly up to about 8000 rpm but then starts to hold back a little, clears, goes again etc up to the red line. It's maybe slightly cleaner running on part throttle than full, but at all throttle positions it still splutters at a constant speed especially around 4500-5000 rpm. It's at least now rideable, but I'd like to get it right. I could jet down and/or change to a leaner needle, maybe put a smaller pilot jet in and I'm fairly sure that would fix it, but it should run ok on the standard settings, so that make me think something still isn't quite right. Is the float height for the power jet carbs correct at 21mm or could the exhausts be blocked? Cheers Mark C
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Post by arrow on Aug 26, 2016 13:16:26 GMT 1
Hi Mark, welcome to the 'wet side'. I would check the stator first. Many stators are starting to play up now. Just rule one thing out at a time, and go from there.
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Post by davecroucher57v on Aug 27, 2016 12:06:09 GMT 1
clean the emulsion tubes/take them out.
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mech73
L plate rider.
Posts: 45
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Post by mech73 on Aug 27, 2016 12:32:00 GMT 1
clean the emulsion tubes/take them out. I've done that already and they were clear including the little holes in the sides, however I didn't check the air feeds to them and I've seen on another forum that this can be an issue. So the carbs are coming off again.
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mech73
L plate rider.
Posts: 45
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Post by mech73 on Aug 27, 2016 12:36:42 GMT 1
Hi Mark, welcome to the 'wet side'. I would check the stator first. Many stators are starting to play up now. Just rule one thing out at a time, and go from there. As it responded so clearly to dropping the needles, the balance of probabilities suggests it's a carb issue, however I've learn't not to rule anything out and I'm aware that apparent carb problems sometimes turn out to be ignition related, so will be reading up on what checks I can do on the stator/CDI etc.
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Post by Tone on Aug 27, 2016 14:51:54 GMT 1
Have you got the carb slides in the correct sides as they are different? You should have the cutaway of the slides facing back towards the airbox with the "Dimples" in the slides for balancing in the windows of the carb body on the RH sides as you're sat on the bike.
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mech73
L plate rider.
Posts: 45
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Post by mech73 on Aug 27, 2016 15:44:05 GMT 1
Have you got the carb slides in the correct sides as they are different? You should have the cutaway of the slides facing back towards the airbox with the "Dimples" in the slides for balancing in the windows of the carb body on the RH sides as you're sat on the bike. Yes both slides are fitted as they should be. On thing maybe worth mentioning, although I can't see that it would be an issue, is that the fuel tap isn't a vacuum one, so has open shut and reserve. The vacuum tube from the RHS carb is still there with a blanking piece blocking the end.
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mech73
L plate rider.
Posts: 45
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Post by mech73 on Aug 27, 2016 23:29:37 GMT 1
clean the emulsion tubes/take them out. I've done that already and they were clear including the little holes in the sides, however I didn't check the air feeds to them and I've seen on another forum that this can be an issue. So the carbs are coming off again. I had a bit of free time this evening so the carbs ore off again. The air feed to the needle jet/emulsion tube (which is a drilling from the float chamber breather circuit) seemed to be ok on both carbs. I could blow through them ok, blocking up the various holes to make sure the others were clear. Whilst they were off I've taken the opportunity to check the fuel level using a clear tube connected to the overflow. With both floats set to 21mm, the fuel level was level with the gasket on one carb and about 0.5mm below the gasket on the other. I've adjusted the floats to make both levels the same and a little lower at about 2mm below the gasket face. The pictures show the level after adjustment. I also found and removed cleaned and replaced the power jets. They were a screw in type and were sized 50 (right) and 55 (left) that slightly surprised me as the spec suggests 60 and 65 and they have been described as pressed in.
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Post by 1966baz on Sept 2, 2016 20:49:09 GMT 1
Welcome to a great forum. Looks like you are doing a very thorough check with the carbs but definitely check the stator as Arrow says. A quality rewind / refurb can make a huge difference on starting and a crisp throttle response.
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Post by budgie on Sept 4, 2016 22:29:58 GMT 1
Did you get to the bottom of this as my N2 is doing something very similar.... Runs great under power, but at constant revs it sounds to be a bit spluttery.... Just done a plug chop today and plugs oily and have done all the usual and checked everything you have , mine is on a freshly built motor, all pressure tested, rebuilt with new crank, rebore done, new Pistons, Std barrels,all new seals etc... Oil pump refurbed by Gary...(Arrow)... Runs fine under power, pulls really well... It is on std jets,needles set in centre position...only thing not std is Micron's...just looking for some direction before I start to strip...
Gavin
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mech73
L plate rider.
Posts: 45
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Post by mech73 on Sept 5, 2016 15:12:48 GMT 1
Did you get to the bottom of this as my N2 is doing something very similar.... Runs great under power, but at constant revs it sounds to be a bit spluttery.... Just done a plug chop today and plugs oily and have done all the usual and checked everything you have , mine is on a freshly built motor, all pressure tested, rebuilt with new crank, rebore done, new Pistons, Std barrels,all new seals etc... Oil pump refurbed by Gary...(Arrow)... Runs fine under power, pulls really well... It is on std jets,needles set in centre position...only thing not std is Micron's...just looking for some direction before I start to strip... Gavin I was away at the weekend and have just got back to it. Carbs are re-fitted, I'm just going to do a few basic electrical tests of the stator etc before the tank goes back on. As long as the rain holds off I'll try it later today. I did measure the float height the normal way just before refitting the carbs and they were about 23 mm from the face of the gasket, so would have been about 23.5 mm with the gasket removed. That sounds quite a way off from the quoted 21 mm, so if it still runs rich it's probably nothing to do with fuel level. Unless 21 mm is wrong for the power jet carbs.
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Post by budgie on Sept 5, 2016 15:31:49 GMT 1
Great thanks for the reply, I will look forward to your results on this one.... Hope you find the cause....
Gavin PS...Take it by the LCFC Avatar your a City fan...?... Are you In Lincolnshire.. I am near Mkt Rasen...
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Post by midlifecrisisrd on Sept 5, 2016 18:02:37 GMT 1
Did you get to the bottom of this as my N2 is doing something very similar.... Runs great under power, but at constant revs it sounds to be a bit spluttery.... Just done a plug chop today and plugs oily and have done all the usual and checked everything you have , mine is on a freshly built motor, all pressure tested, rebuilt with new crank, rebore done, new Pistons, Std barrels,all new seals etc... Oil pump refurbed by Gary...(Arrow)... Runs fine under power, pulls really well... It is on std jets,needles set in centre position...only thing not std is Micron's...just looking for some direction before I start to strip... Gavin I know it's different but that was the bane of my 385 with pwk's Was worst running at a steady 4k. Dropping the pilots cured it Microns are known for the 5.5k stuttering. Some say dropping the needle to lean it helps Just be careful as some have seized as lean at top end on standard jetting. Steve
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Post by budgie on Sept 5, 2016 19:58:30 GMT 1
Hi Steve Thanks for the input, it will just not run clean, at any revs, unless it's pulling, it is great when under throttle... Just sounds wrong.... It's totally std apart from the Micron's....but plugs are oily not just dry and rich, did have a thought as when I bought it, it had resistor caps and non resistor plugs in it... Did try resistor plugs in aswell and was less happy, so have reverted back to non resistor plugs....so didn't know if I have issues with my CDI or stator..... Just a thought....and I'm running 9ES plugs.... I will drop the needles and plug chop it.... Thanks again.... Gav
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Post by midlifecrisisrd on Sept 5, 2016 20:09:48 GMT 1
Hi Steve Thanks for the input, it will just not run clean, at any revs, unless it's pulling, it is great when under throttle... Just sounds wrong.... It's totally std apart from the Micron's....but plugs are oily not just dry and rich, did have a thought as when I bought it, it had resistor caps and non resistor plugs in it... Did try resistor plugs in aswell and was less happy, so have reverted back to non resistor plugs....so didn't know if I have issues with my CDI or stator..... Just a thought....and I'm running 9ES plugs.... I will drop the needles and plug chop it.... Thanks again.... Gav Hi Gav Ypvs should have the red caps (can't remember if red or black has the resistors) and BR8ES plugs. The 9 may not be helping. Steve
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mech73
L plate rider.
Posts: 45
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Post by mech73 on Sept 5, 2016 20:10:54 GMT 1
With the float adjustment dropping the fuel level, I took it for about a 20 mile ride and could notice no difference at all.
Air screws 3 turns out, needles on top (weakest) clip and although rideable, it still feels slightly rich at nearly all throttle positions. There's one sweet spot at about 1/4 ish throttle where it revs cleanly to about 9000 rpm. At all other throttle positions it starts holding back at about 7500 rpm.
When I got back I tried the needle back in position 2, which made it much worse and exactly as it was when I started.
My conclusion is that fuel level is not the issue.
I also checked the stator resistances. All three coils (lo, high and pulse) were within spec, at least to the tolerance of my meter. I know this doesn't prove the stator is good, so I'm far from ruling that out yet, but it does seem a carb issue.
I haven't worked out where to go next. I may try some new pilots a size lower. Three turns out for the air screw is probably a clue that something is amiss there.
I also haven't actually looked at the stator or checked the timing, so I ought to do that first.
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mech73
L plate rider.
Posts: 45
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Post by mech73 on Sept 5, 2016 20:14:39 GMT 1
Great thanks for the reply, I will look forward to your results on this one.... Hope you find the cause.... Gavin PS...Take it by the LCFC Avatar your a City fan...?... Are you In Lincolnshire.. I am near Mkt Rasen... Originally from Lincolnshire (Cherry Willingham) and went to school in Mkt Rasen. Now in Hampshire although I still have relatives near Lincoln, so go back quite a lot.
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Post by midlifecrisisrd on Sept 5, 2016 20:18:57 GMT 1
If the stator is checking out OK and the cars are on standard jetting with everything else is standard I'd be looking at the exhausts.
Steve
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Post by midlifecrisisrd on Sept 5, 2016 20:21:28 GMT 1
Oh and one more thing
Was the new filter genuine
I bought a "hi flow" filter for mine and it ran richer than the genuine one which is about a fiver.
Try taking the snorkel out the inside of the airbox and see how it runs
Steve
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mech73
L plate rider.
Posts: 45
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Post by mech73 on Sept 5, 2016 20:28:27 GMT 1
Oh and one more thing Was the new filter genuine I bought a "hi flow" filter for mine and it ran richer than the genuine one which is about a fiver. Try taking the snorkel out the inside of the airbox and see how it runs Steve Yes it was genuine. Taking the snorkel out is an easy thing worth trying, so I'll do that.
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mech73
L plate rider.
Posts: 45
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Post by mech73 on Sept 5, 2016 20:32:34 GMT 1
If the stator is checking out OK and the cars are on standard jetting with everything else is standard I'd be looking at the exhausts. Steve Not an easy thing to check as the baffles don't seem to be removable. To clean them I guess it's a blow lamp job? The end cans seem to be plated with something that makes them look aluminium although they're not as a magnet sticks.
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Post by midlifecrisisrd on Sept 5, 2016 20:40:30 GMT 1
If the stator is checking out OK and the cars are on standard jetting with everything else is standard I'd be looking at the exhausts. Steve Not an easy thing to check as the baffles don't seem to be removable. To clean them I guess it's a blow lamp job? The end cans seem to be plated with something that makes them look aluminium although they're not as a magnet sticks. Plug the header then fill through the tail with caustic soda and leave for 24 hours or so Steve
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Post by budgie on Sept 6, 2016 20:14:55 GMT 1
Hi Steve Thanks for the input, it will just not run clean, at any revs, unless it's pulling, it is great when under throttle... Just sounds wrong.... It's totally std apart from the Micron's....but plugs are oily not just dry and rich, did have a thought as when I bought it, it had resistor caps and non resistor plugs in it... Did try resistor plugs in aswell and was less happy, so have reverted back to non resistor plugs....so didn't know if I have issues with my CDI or stator..... Just a thought....and I'm running 9ES plugs.... I will drop the needles and plug chop it.... Thanks again.... Gav Hi Gav Ypvs should have the red caps (can't remember if red or black has the resistors) and BR8ES plugs. The 9 may not be helping. Steve Hi Steve I have just checked and I am on Red plug caps with B9ES plugs.... The manual says BR9ES for an N2.but mine does not like resistor caps and resistor plugs..... Do you think I will be better with 8's..?... I have dropped the needle one tonight and will run tomorrow eves...but the manual says 4th from top on needle clip, well I am now 2nd from top...we will see how it goes... Gavin
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Post by budgie on Sept 6, 2016 20:18:21 GMT 1
Great thanks for the reply, I will look forward to your results on this one.... Hope you find the cause.... Gavin PS...Take it by the LCFC Avatar your a City fan...?... Are you In Lincolnshire.. I am near Mkt Rasen... Originally from Lincolnshire (Cherry Willingham) and went to school in Mkt Rasen. Now in Hampshire although I still have relatives near Lincoln, so go back quite a lot. Sorry for hijacking your thread Mech73... But I guess it's in common interest.....So you went to De Aston... What years... I was a William Farr man myself... But moved near Rasen 15 yrs ago...Grew up in Scothern...spent a bit of time round Cherry and Reepham, and Fiskerton...left Will Farr in 83... Gavin
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mech73
L plate rider.
Posts: 45
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Post by mech73 on Sept 6, 2016 20:40:52 GMT 1
Originally from Lincolnshire (Cherry Willingham) and went to school in Mkt Rasen. Now in Hampshire although I still have relatives near Lincoln, so go back quite a lot. Sorry for hijacking your thread Mech73... But I guess it's in common interest.....So you went to De Aston... What years... I was a William Farr man myself... But moved near Rasen 15 yrs ago...Grew up in Scothern...spent a bit of time round Cherry and Reepham, and Fiskerton...left Will Farr in 83... Gavin No problem, common interest as you say. I was at De Aston 71-76, then Ruston Bucyrus. Quite a few from Scothern went to De Aston as well and our bus called there then went to Rasen via Stainton, Snelland and Wickenby. I left in 86, but my Mother and Brother still live in Saxilby and I often come up for the football and the odd bike event (Wolds run, Cadwell classic track day and the Eagle FS1E rally).
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Post by budgie on Sept 6, 2016 21:02:56 GMT 1
Well looking at the dates you will have been at De Aston in grammar school days.. My eldest Bro went there I think he left similar dates to you..David Bird...was a good era, as he and his mates were always around ours with a real mix of bikes.. From Garelli Tiger Cross to Rd400's.. I am 7 yrs younger than him and grew up with a smell of two stroke... Always something stripped on the drive...
Small world
Gav
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Post by midlifecrisisrd on Sept 6, 2016 21:16:37 GMT 1
Hi Gav Ypvs should have the red caps (can't remember if red or black has the resistors) and BR8ES plugs. The 9 may not be helping. Steve Hi Steve I have just checked and I am on Red plug caps with B9ES plugs.... The manual says BR9ES for an N2.but mine does not like resistor caps and resistor plugs..... Do you think I will be better with 8's..?... I have dropped the needle one tonight and will run tomorrow eves...but the manual says 4th from top on needle clip, well I am now 2nd from top...we will see how it goes... Gavin I thought all ypvs were on BR8ES I was always told that non resistor plugs caused spurious signal's to the power valve which won't help Try some 8's Steve
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Post by budgie on Sept 6, 2016 21:32:53 GMT 1
Hi Steve I have just checked and I am on Red plug caps with B9ES plugs.... The manual says BR9ES for an N2.but mine does not like resistor caps and resistor plugs..... Do you think I will be better with 8's..?... I have dropped the needle one tonight and will run tomorrow eves...but the manual says 4th from top on needle clip, well I am now 2nd from top...we will see how it goes... Gavin I thought all ypvs were on BR8ES I was always told that non resistor plugs caused spurious signal's to the power valve which won't help Try some 8's Steve Cheers Steve, I will get some and plug chop it...!! Gavin
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mech73
L plate rider.
Posts: 45
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Post by mech73 on Sept 6, 2016 21:41:22 GMT 1
Well looking at the dates you will have been at De Aston in grammar school days.. My eldest Bro went there I think he left similar dates to you..David Bird...was a good era, as he and his mates were always around ours with a real mix of bikes.. From Garelli Tiger Cross to Rd400's.. I am 7 yrs younger than him and grew up with a smell of two stroke... Always something stripped on the drive... Small world Gav I do remember your brother. Have you still got the Brockhouse Corgi or the Sparkbrook? It may have been my Tiger Cross on one of the rare occasions it was running. Tell him Mark Chambers.
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Post by budgie on Sept 6, 2016 22:10:04 GMT 1
Hi Mark
They were the good old days, your name rings a bell, you obviously must of been round our place at some time to know about dads old bikes....amazed you remembered...... What did you run...? I may remember more from the bike...I guess the bike I remember the most was a lad on a Lovely blue Gitaine ....it was gorgeous and went like mad....
Don't see much of Dave now.. Although only a few miles down road... Family's ehh....don't always get on...
Still got both of the bikes.... How funny you remember.... Along with another 50 plus bikes between middle brother and myself..... Think Daves got a BMW and a XS650...
Gavin
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