phil38
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Post by phil38 on Oct 7, 2013 13:12:47 GMT 1
Took my N2 YPVS out on Saturday for its first proper ride. It's had a rebuild including honed bores & new rings, so I was running it fairly gently (as per the running in guide on this forum). Anyway, i did about 30 miles between 50 & 30mph, and most of the time the temp gauge was sitting about 3/4. We I cam back into town them temp was a bit above this (maybe just less than 1/4 inch from the red).
When I rebuilt the engine, I made sure all the cooling channels in the head were clean & also flushed the rad with a hose pipe. I haven't disturbed the water pump or used any chemical flush yet....
Not sure what temperature the bike should run at, but it seems hot to me considering how gently i'd been riding.
Next move will be to run some Holts rad flush through the system in case the radiator is scaled up.
Anyone got any other thoughts or experience they can share?
p.s. The stat opens when you put it in hot water and I filled the system pretty carefully and topped it up after the first heat cycle after the rebuild.
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phil38
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Post by phil38 on Oct 7, 2013 13:36:26 GMT 1
Could be an air leak,carb/induction related You ain't used Yambits crank seals have you  Ha! No, genuine Yamaha seals. Bike seems to be running nicely, so I don't think it's running lean. I think it's cooling system related. |
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Post by Taylormade on Oct 7, 2013 23:16:25 GMT 1
May or may not be relevant but when riding my LC gently and cruising around the 30 - 50 mph it's gets quite warm! soon as I thrash it, she cools right back down again!
I know you can't thrash it at the mo as your running in but I found that strange, yours does seem to be a little hot though...... Hope you find a solution.
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Post by Denzil on Oct 7, 2013 23:43:07 GMT 1
Hi phil38, I got the same bike as you fella and had the same problem. I would take mine out and it would be in the red all the time. I cured it by ensuring the correct jets where in the carbs and putting the needle-circlip on the middle notch. I ran it on comp 2 oil NOT Fully synthetic oil on running in. It was then a different bike. The temp was down to 1/4 to enable me to do a 500 mile run in.
It now runs ace I can take it on a 100 mile run thrashing it to 9000 in places and it still runs around the quarter mark if I'm in town then it's up to half. Maybe worth a shot.
Standard air box with filter. No additional holes etc.
Oil pump breathed on by Arrow, well worth it in my opinion.
Cheers
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phil38
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Post by phil38 on Oct 8, 2013 12:32:05 GMT 1
Hi phil38, I got the same bike as you fella and had the same problem. I would take mine out and it would be in the red all the time. I cured it by ensuring the correct jets where in the carbs and putting the needle-circlip on the middle notch. I ran it on comp 2 oil NOT Fully synthetic oil on running in. It was then a different bike. The temp was down to 1/4 to enable me to do a 500 mile run in. It now runs ace I can take it on a 100 mile run thrashing it to 9000 in places and it still runs around the quarter mark if I'm in town then it's up to half. Maybe worth a shot. Standard air box with filter. No additional holes etc. Oil pump breathed on by Arrow, well worth it in my opinion. Cheers Cheers!. The best LC in my opinion! The carbs do have the correct main jets (185s) & needles are mid position (I think I checked this!). It was "running" with 180 mains when I got it. Not sure I checked the pilots (carb rebuild was a while ago!). Ait box is standard, as are the pipes. Oil pump has had the arrow treatment with 10% increased flow. Am currently running on Castrol Power 1 Racing 2T which is fully sythetic. I have read that it's better to use a semi-synth for running in, which I kind of understand but I'm not convinced will make a great deal of difference in reality. When it was running hot, what were the carb settings & jet sizes you had and was the the only change you made to cool it down? |
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Post by cinder on Oct 8, 2013 12:37:20 GMT 1
is your thermostat ok,does the cooling system need bleeding?how tight were the pistons in the bore?
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phil38
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Post by phil38 on Oct 8, 2013 12:50:17 GMT 1
quote author=" cinder" source="/post/198017/thread" timestamp="1381232240"]is your thermostat ok,does the cooling system need bleeding?how tight were the pistons in the bore?[/quote] Stat opens fully in boiling water & cooling system is full & without airlocks as far as I can tell. Pistons are originals with new Riken rings from Norbo. Ring gaps were within spec in the bore. Bores are standard size - got away with a hone which puts them close to the upper limit on (standard) bore size, so not overly tight. I think I'll try the following: 1. Double check for air locks & re check cooling system levels 2. See if I can feel any cold spots on the rad when it's warmed up 3. Use the holts 2 part rad flush (this involves idleing the motor for 30 mins which I'm not mad keen on with a newly build engine, so may run for 10 mins, off for 5, 10 mins off for 5 with the stat removed) 4. Check pilot jet sizes and needle positions (are the pilot jets stamped with the size? - can't recall noticing when they were apart) Is it worth looking at the water pump impellor by removing the cover - am I likely to be able to notice if anything is wrong? Are there generally issues with the pump? Haynes book of wisdom says they only go wrong when the bearing seal fails and puts coolant into the oil.... |
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Post by Denzil on Oct 8, 2013 23:51:49 GMT 1
Hi chaps, a resident geru called Mutsnutts also gave some advice to me but basically the carbs as you have yours, standard F2 exhausts, needle on middle clip.
Good flow on the radiator maybe take off the grill just to see if better flow. The main one was Never use FULLY synthetic as the pistons are tight the Fully synthetic just glazes the bores and makes it run hot you need semi synthetic until you have run it in.
That's all I did and I ran it on super unleaded.
Cheers
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Post by muttsnuts on Oct 10, 2013 11:53:36 GMT 1
yup, which radiator cover are you running, standard or a rentec, if its a rentec, take it off, if your using fully synthetic, drop it out and replace with semi synthetic until you get some miles on the engine otherwise the bores will glaze incorrectly, this causes 2 problems;
1. The engine runs hotter as it can't disipate the heat into the cylinder walls
2. Doesn't allow the piston rings and bores to bed in together, which means the friction caused by them not being bedded in correctly is greater, therefore equals hotter running and also the bores won't retain the oil for lubrication properly, so even more heat being produced
The other thing you need to bear in mind is that your rebore might have been done a tad on the tight side, did you measure the bore/piston clearance and also the ring gaps?, if these are tight then you get a double wammy, first they run really hot due to high friction forces, secondly they take forever to bed in and using fully synthetic means it probably won't bed in at all, alos have you got the oil expander ring fitted under the bottom ring?, if so this will also increase the friction as it makes the bottom ring push harder onto the bore
For those who are about to jump in about racers who just rebore and go and use fully synthetic, you will find that they have there rebores done slightly bigger and only use the top ring on the piston normally
Anyway, I'd be checking the rad cover, changing the 2T oil and also check for air locks, squeeze the coolant pipes while the bike is running and also make sure the thermostat is working correctly
HTH
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Post by looey on Oct 10, 2013 12:29:46 GMT 1
Renntec have modified the grills now, so they have larger rectangular holes as opposed to the small round holes they had before.
I'm running my YPVS engine in at the moment with a new style Renntec rad grill fitted and it runs around 1/4 on the gauge most of the time, occasionally going upto around 1/3 if I get in some traffic or slow riding.
Probably not your problem but a bit of info that might help you or someone else ?.
Good luck sorting it.
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Post by wonkywheel on Oct 10, 2013 19:47:27 GMT 1
Not unless there is a cooling or carb problem, just plodding around the engine can run a tad hot, due to less air force circulating the engine, even though its and LC. It's getting a bit Cooler now, so you will soon find out if you do have a cooling problem. What's the problem with running in with fully synthetic? Can it run too hot,or rings don't bed in? |
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phil38
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Post by phil38 on Oct 10, 2013 22:27:19 GMT 1
Cheers guys,
Am running the standard rad grill, not rentec or anything else like that.
Engine has not been rebored, just honed to get rid of some light scuffing. Bores were measured after honing and around max limit for standard (I.e. Just off needing a rebore). Ring gaps were ok. Am running with the expander behind the bottom ring.
If we get any decent weather I'll give it another run and double check for airlocks, maybe flush the rad and then move on to the list of suggestions.
I'll let you know how it goes. I suspect with the weather turning to crap, it'll be run in by about April !
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Post by hampo on Oct 10, 2013 22:34:24 GMT 1
Hi phil38, and hi to all from a new membrane. The only time my F2 overheats is when the head gasket has gone. as a new owner I was baffled by the way it would go into the red & spunk coolant all over the lhs when i took it over 80. With all rspect to the replies so far, I had a tight rebore & gave it a careful run in from newcastle to malton for a full on dyno session (thank muttnuts!) and home again with no probs, pattern gaskets would go with depressing regularity (less than 1k miles) until i was told how to pre-treat them. if it was running ok before on the same carbs i'd think you can discount jetting. Has the coolant level gone down? My 2d worth (make that 1d). Nice bike, good luck sorting it
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phil38
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Post by phil38 on Oct 10, 2013 22:40:55 GMT 1
Not unless there is a cooling or carb problem, just plodding around the engine can run a tad hot, due to less air force circulating the engine, even though its and LC. It's getting a bit Cooler now, so you will soon find out if you do have a cooling problem. What's the problem with running in with fully synthetic? Can it run too hot,or rings don't bed in? There is a theory that fully synthetic stops the rings bedding in as it's so good you get very little wear. I understand the logic but have heard different views on this. A guy I work with is ex Stan Stevens. He said most of the racers he know used to swear by Castrol R, but the only time he tried running in a 2 stroke it seized. On Another forum, there was a guy who reckoned he always ran in engines on synthetic and never saw any evidence of bore polishing (he was a mechanic in a skidoo dealers in the US) I did get an opinion from a guy I know who is an expert on pistons for an engineering consultancy firm. His view was: --------------- There are always noises around either way forward with the engine oil in a new engine I would say that my personal experience is that the risk of piston / bore / ring scuff early life in these small 2 strokes is high and if you can assist the bedding in process with good quality oil then you should do it. The 2T fully synthetic would be my recommendation. The semi-synthetic or mineral oils will likely be OK if the component quality is good but I would always er to the side of caution if its your own piece of kit. If you drive like a granny then it will likely never bed in well BUT if you drive with the spirit intended then it certainly will. The synthetics do make a difference BUT the bedding in still occurs. ------------------------- So, fuctifino! |
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phil38
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Post by phil38 on Oct 10, 2013 22:47:59 GMT 1
Hi phil38, and hi to all from a new membrane. The only time my F2 overheats is when the head gasket has gone. as a new owner I was baffled by the way it would go into the red & spunk coolant all over the lhs when i took it over 80. With all rspect to the replies so far, I had a tight rebore & gave it a careful run in from newcastle to malton for a full on dyno session (thank muttnuts!) and home again with no probs, pattern gaskets would go with depressing regularity (less than 1k miles) until i was told how to pre-treat them. if it was running ok before on the same carbs i'd think you can discount jetting. Has the coolant level gone down? My 2d worth (make that 1d). Nice bike, good luck sorting it When it was last running, it overheated like a b*****d and spat it's coolant everywhere. When I got into the engine I found that ther was a missing head stud (some previous t**t of an owner had todged the head bolt in with silicon!). All that's sorted now and running with new yamaha gaskets and a full set of studs as we'll has honed bores, new rings, rebuild power valves with remachined bushed and new seals, painted barrels and head, rebuilt bottom end with new crank seals and new output shaft bearing… Once you start with the engine it gets expensive!! |
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Post by muttsnuts on Oct 11, 2013 8:49:20 GMT 1
just a thought, did you check the head to see if it was warped, you mentioned that the previous owner had bodged one of the studs, knowing that I'd have to say the head is suspect, if you didn't get it checked for being warped, then that would be my first port of call as all of your symptoms do suggest that could be your cause
Its always hard diagnosing faults over forums/emails like this as your not always armed with all of the info, given the above, I'd ignore all of the previous stuff (including mine!) and check that head if it hasn't been done
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Post by Denzil on Oct 11, 2013 9:29:25 GMT 1
Sounds very much like the head as Muttsnuts has said. Best to strip it and get it checked out fella.
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phil38
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Post by phil38 on Oct 11, 2013 13:11:54 GMT 1
just a thought, did you check the head to see if it was warped, you mentioned that the previous owner had bodged one of the studs, knowing that I'd have to say the head is suspect, if you didn't get it checked for being warped, then that would be my first port of call as all of your symptoms do suggest that could be your cause Its always hard diagnosing faults over forums/emails like this as your not always armed with all of the info, given the above, I'd ignore all of the previous stuff (including mine!) and check that head if it hasn't been done I checked the head, it was fine. I don't think there's anything seriouly wrong, it's not gassing into the coolant or anything, just hotter on the gauge than I would have expected for gentle runnning! Thanks for the help - head is certainly a possibility (and overheating was the main sympton last time). I'll check the coolant is still at the same level as before and take it for another run.  Cheers. Phil |
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higgsy
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Post by higgsy on Oct 11, 2013 21:46:17 GMT 1
Yep, honed to a slightly bigger clearance, depending on which pistons are used, two rings though, I found the blow past even with a reduced ring gap was too much. Might have been better with a designated one ring piston but didn't work on the Seizecos or Mitakas. Honed bigger because there isn't really enough time to spend running the bike in, and there is a theory concerning frictional losses etc.
There is definatly something in the not using fully synthetic for running in, after all you are trying to wear the high spots off the barrels. Not so important if the barrel has been honed correctly afterwards, the correct method is to bore the cylinder then hone to final size. Some companies unfortunately just bang the boring bar through then rub a quick hone down it, or not even bother honing it. A correctly bored and honed cylinder will last a long time, the pattern is still evident on my race TZR after three seasons :-)
Anyway at low revs all my RD's seem to run hot, even with the big rad on the N2 racer, must be the pump not being that efficient at lows revs I guess. A 50 degree Thermostat helps things as does a big flow impeller, the angled F2 rad guard seems to make them run a tad warmer, it certainly seems not to scoop cold air in IMO
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Post by yamanastic on Oct 12, 2013 1:36:47 GMT 1
Hi phil38 been reading through your post and was wondering when you rebuilt the top end did you heat the bike up to working temperature and let it cool down till it's cold again and re-torque the cylinder head nuts, I'm thinking you might have already done this but no harm in asking.
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phil38
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Post by phil38 on Oct 12, 2013 20:10:25 GMT 1
Hi phil38 been reading through your post and was wondering when you rebuilt the top end did you heat the bike up to working temperature and let it cool down till it's cold again and re-torque the cylinder head nuts, I'm thinking you might have already done this but no harm in asking. Yep, did this. They didn't move at all! |
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phil38
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Post by phil38 on Oct 12, 2013 20:16:52 GMT 1
Update:
Went for another ride today, about 30 B road miles. Cooling gauge went to about 2/3 then dropped to about half way when the stat opened. The gauge stayed between 1/3 and 2/3 most of the time, the 2/3 being when I got held up by grannies in Toyota Aygos/ Honda Jazz's! It only got to about 3/4 when I came back into town...
Allowed the engine to review to 6K in the first couple of gears and cruised at about 4.5K.
It was a lot cooler this weekend than last (about 10deg C), so it may be better just because it's getting more cold air, or it may be that then engine's starting to loosen up a bit. (Judging by how loudly the wife screamed when I shoved my hands down her back when I got in, I suspect it may be due to the outside temp!!)
Still sticking with the synthetic oil for the time being!
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