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251LC
Feb 27, 2021 15:23:06 GMT 1
Post by Tobyjugs on Feb 27, 2021 15:23:06 GMT 1
There is BEET ducktail, its a bit wild tho as its one of those that sticks out and up at the back. Its cool, but not for me. I may well one day get the side panels and the front guard, but for now Im happy to just tip the nod to the JDM style on this one They were just ahead of the time in creating extra down force
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251LC
Feb 27, 2021 20:40:02 GMT 1
JonW likes this
Post by abar121 on Feb 27, 2021 20:40:02 GMT 1
Haha. Love the paint scheme.
I think I'll have to do one at some stage.
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Post by JonW on Feb 27, 2021 22:46:01 GMT 1
There is BEET ducktail, its a bit wild tho as its one of those that sticks out and up at the back. Its cool, but not for me. I may well one day get the side panels and the front guard, but for now Im happy to just tip the nod to the JDM style on this one They were just ahead of the time in creating extra down force Haha, too funny (but yeah im going to agree with you Tony!)
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Post by JonW on Jul 27, 2021 14:16:50 GMT 1
A little upgrade and fixing of a safety issue this week. To save my life i ditched the leaking Legend brake hoses and swapped in some new Yambits made in uk units. Much better, I can rely on these now. FWIW I mentioned in a seperate thread that the Legend hoses were 'sweating' and when I sucked out the correct Dot3 fluid it came out very dark brown, almost black. Sigh. Please dont trust your life to shit hoses... The upgrade I also did was to replace the Brembo (Ducati/KTM) master cylinder sight glass (left of photo) with one of Alan's new units. Sooo much better. Huge thanks to Al for making these! I also fitted one of his oil tank straps as well at the same time.
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251LC
Sept 17, 2021 14:04:53 GMT 1
Trent likes this
Post by JonW on Sept 17, 2021 14:04:53 GMT 1
Decided that before I run this bike up I would finally do something about the PVs as they dont feel right to me as they sound like they are binding when the PV clean cycle runs. I should have sorted these when I built the engine but thought cos there were so many new parts in the PVs that it was just 'tight', but Ive come to realise they are binding. I tried spinning them to bed them in but to no avail, the clean cycle when switched on runs very slowly due to the drag and thats with clean and lubed parts, it would only get worse. hmm... So, Ive bitten the bullet and got on with stripping... I got to this stage before realising that the original job is no longer on the table... ...that issue is long forgot because of this! OMFG! There is a crack in the cylinder liner! This is big enough to catch a nail at the top and lessens as the crack closes. I tried in vain to see if it was a scratch or something, but no... sigh, it's not. These are rebored cyls on +1.5mm. I had them done ages back to match the new TKRJ pistons and they were fine. But now there is a bloody crack in this one. How the hell has that happened??? Ive never seen that before on a bike thats been bored and not run. You'd have to do something quite dramatic to have this happen, yet all thats been done is to build the engine and torque up the head etc. Sigh... Anyone have a right side (when sat on the bike) 51L cylinder?
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251LC
Sept 17, 2021 14:44:19 GMT 1
via mobile
Post by midlifecrisisrd on Sept 17, 2021 14:44:19 GMT 1
I feel your pain bud - ouch
There is only that damaged one I see on eBay
Ironically it's in Aus 🙄
Steve
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251LC
Sept 17, 2021 16:28:48 GMT 1
Post by chippy348 on Sept 17, 2021 16:28:48 GMT 1
OMFG! There is a crack in the cylinder liner! This is big enough to catch a nail at the top and lessens as the crack closes. I tried in vain to see if it was a scratch or something, but no... sigh, it's not. These are rebored cyls on +1.5mm. I had them done ages back to match the new TKRJ pistons and they were fine. But now there is a bloody crack in this one. How the hell has that happened??? Ive never seen that before on a bike thats been bored and not run. You'd have to do something quite dramatic to have this happen, yet all thats been done is to build the engine and torque up the head etc. Sigh... Anyone have a right side (when sat on the bike) 51L cylinder? I am sure I know what that is, and I dont think it is a crack ! PM if you like and i will give you my thoughts
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fubars
Drag-strip hero
Posts: 294
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Post by fubars on Sept 17, 2021 17:49:43 GMT 1
Looks almost like a join 😕
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251LC
Sept 17, 2021 17:58:51 GMT 1
via mobile
steve h likes this
Post by midlifecrisisrd on Sept 17, 2021 17:58:51 GMT 1
It does seem weirdly straight and unless I'm wrong it's down the side
Steve
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fubars
Drag-strip hero
Posts: 294
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Post by fubars on Sept 17, 2021 18:03:11 GMT 1
It does seem weirdly straight and unless I'm wrong it's down the side Steve That's what I thought, looks almost like a sleeve.
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251LC
Sept 17, 2021 19:06:32 GMT 1
Post by headcoats on Sept 17, 2021 19:06:32 GMT 1
Could a boring bar or the honing tool cause it ?
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Post by mickross355 on Sept 17, 2021 21:53:54 GMT 1
That’s from the boring bar on retract. They get to the bottom of the hole and stop spinning to retract. It looks like they haven’t left enough material for honing afterwards. You can still see the finish left by the boring operation.
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251LC
Sept 17, 2021 22:30:20 GMT 1
Post by donkeychomp on Sept 17, 2021 22:30:20 GMT 1
Can that be saved?
Alex
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Post by mickross355 on Sept 17, 2021 22:42:17 GMT 1
Need to check piston to bore clearance. Will probably need to go to the next size up I’d be check the other side too
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251LC
Sept 18, 2021 0:02:18 GMT 1
Post by JonW on Sept 18, 2021 0:02:18 GMT 1
Interesting thoughts guys.
What's interesting is that I hadnt seen this when I A, got the cyls back from the reborer and B, fitted them. This makes me think it wasnt there (or at leat wasnt obvious) at that time.
The other side is fine from what i can tell.
I do agree it does look like it wasnt honed in the pic hmm...
Im not sure I'd want to go much bigger, these are on 1.5 over already, whats the thoughts on running it?
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Post by mickross355 on Sept 18, 2021 0:06:30 GMT 1
Jon I’d me more worried about the lack off cross hatch than the mark from the boring bar. As long as it’s below the surface (which it should be, as it was honed after)the rings won’t catch. You have a minuscule reduction in ring sealing performance. Can you do a leak down test and compare it to the other cylinder?
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Post by mickross355 on Sept 18, 2021 0:11:46 GMT 1
51L is the boysen port cylinders?
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251LC
Sept 18, 2021 0:55:57 GMT 1
Post by JonW on Sept 18, 2021 0:55:57 GMT 1
51L is the boysen port cylinders? Thanks Mick. I'll have to get them honed and checked out I guess anyway. I agree the loss will be minimal, annoying but if i can save them i would like to, as yes these are the Boysen port 250s.
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251LC
Sept 18, 2021 9:17:08 GMT 1
Post by jon on Sept 18, 2021 9:17:08 GMT 1
Just a though but may be of use?
Have you tried comparing the 1.5mm over TKRJ pistons to other brands?
I have found considerable difference between Japanese Mitaka, OEM banshee and forged pistons all claiming to be 0.5mm over.
Slightly bigger pistons would require more boring/honing.
Jon
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251LC
Sept 18, 2021 9:39:40 GMT 1
Post by reedpete on Sept 18, 2021 9:39:40 GMT 1
John, if you can feel it with your finger and it really was a crack , it should also run the depth of the liner at the head gasket surface. Clean it up and rinse a bit there and see what it looks like. If I zoom your photo, there’s nothing conclusive. You can see a little bit of darkness but it might just be anything.
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251LC
Sept 18, 2021 9:58:11 GMT 1
Post by JonW on Sept 18, 2021 9:58:11 GMT 1
Just a though but may be of use? Have you tried comparing the 1.5mm over TKRJ pistons to other brands? I have found considerable difference between Japanese Mitaka, OEM banshee and forged pistons all claiming to be 0.5mm over. Slightly bigger pistons would require more boring/honing. Jon Good thought Jon, tho Ive no idea about other 1.5mm oversize 250 pistons sizes, I only ever use TKRJ in 250s.
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251LC
Sept 18, 2021 10:00:16 GMT 1
Post by JonW on Sept 18, 2021 10:00:16 GMT 1
John, if you can feel it with your finger and it really was a crack , it should also run the depth of the liner at the head gasket surface. Clean it up and rinse a bit there and see what it looks like. If I zoom your photo, there’s nothing conclusive. You can see a little bit of darkness but it might just be anything. Thats a very good point. I need to get a loupe on it and see that top edge of the liner. I do agree that this would confirm if this is a tool mark or a crack. I'll cross my fingers and get on that tomorrow. -- Thanks for all the input guys! Really appreciated!
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251LC
Sept 18, 2021 11:13:08 GMT 1
via mobile
Post by galant2nz on Sept 18, 2021 11:13:08 GMT 1
Hi Jon, if you need a barrel let me know I have a few pairs of the 51L’s just across the ditch in NZ. Cheers
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Post by mickross355 on Sept 18, 2021 11:43:25 GMT 1
You could always pressure test the barrel to really confirm if it’s cracked or not. Easy to make up some plates to block off the water jackets
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251LC
Sept 18, 2021 11:47:13 GMT 1
Post by Tobyjugs on Sept 18, 2021 11:47:13 GMT 1
Hi Jon just clean the top of the liner well and get some crack detector spray. You will soon see if it's a crack or not. Easy enough to find the spray if you know some welders.
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251LC
Sept 18, 2021 13:42:50 GMT 1
Post by JonW on Sept 18, 2021 13:42:50 GMT 1
Hi Jon, if you need a barrel let me know I have a few pairs of the 51L’s just across the ditch in NZ. Cheers Very kind of you to offer mate.
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251LC
Sept 18, 2021 13:45:09 GMT 1
Post by JonW on Sept 18, 2021 13:45:09 GMT 1
You could always pressure test the barrel to really confirm if it’s cracked or not. Easy to make up some plates to block off the water jackets Good idea, I am hopeful this is a boring bar mark, but good to have a road map from here if not. Hi Jon just clean the top of the liner well and get some crack detector spray. You will soon see if it's a crack or not. Easy enough to find the spray if you know some welders. Thanks Tony, good idea. I know a few guys, hopefully someone has some.
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Post by JonW on Sept 20, 2021 3:19:02 GMT 1
Cylinder UPDATE:
After a weekend off off bikes and doing some gardening (im knackered!), Ive headed back into the garage...
There is some 'kinda good news' in that when viewed with a jeweller's loupe the 'crack' in my 51L cyl is not actually a crack. I can see after a clean up that there is no radial line emanating from the edge of the 'crack' across the top of the liner. As was pointed out here, if the mark shown in the photo up the wall of the cyl was a crack the it would be all the way through the liner and show as a line on the 'end' of the liner itself as the broken ends would be separating, leaving a line. The other giveaway I believe is that the line of the 'crack' also very straight, nature never works in straight lines, there is always some kind of wobble.
So, this is not a crack then. But what is it?
Well, those who put their money on a careless boring job I believe you were right. The mark shown was made when the boring cutter was stopped and raised to bring it up and out of the cylinder at the end of the boring pass, in doing so it left a gouge that started where it contacted the wall and got deeper by the amount of angle the bore was not the same alignment as it was when the boring pass was made.
Ok... hmm... No we know this, it's not wonderful news... but it's not catastrophic for this cylinder like a crack would be.
So, what happened means that the boring job was certainly not the greatest of work. The guy who did it was a super old school operator who had closed his rebore business and was retired, just doing jobs for people he knew. Lovely guy but was obviously past his prime, he's since sold his machinery and fully retired. I feel that's for the best after seeing this. He did more cylinders after these for me and I believe they are fine so this could have just been a bad day I guess. hmm.. lets hope so, most of the other work he did are now inside engines. I'd like to say that I checked them over and that I never noticed any issues, but I also never saw anything wrong with these even when I was cleaning them up when back from rebore, masking and painting them and later fitting em. The gouge must have been superclean and now has some dirty oil in it so shows up is all I can think.
FYI The cylinder also looks in the photo like its not been honed, but in real life it does have light honing marks. I would have questioned the lack of honing when I collected these so I knew it had them, I think its just the hone was light and the bore marks show more in the photo due to the LED lighting I use to see when working on bikes which lighted the photo.
What will I do now?
A couple of people in the know reached out to me and have advised me that for sure the best idea is to check the bore size and if possible hone to remove the gouge and rebore if that makes them too big.
Sadly, I don't have that luxury with the 250 YPVS cylinder though as these are already 1.50 over and I dont believe there is a +1.75 or +2.00 piston kit and even if there is, its awfully large for the cylinder, leaving a thin liner as we know. Plus, there could be PV issues and im not grinding a good set of PVs etc.
As it's not like I have lots of bores left, I'm really at the end of life for these. I could have these re-sleeved but that would cost more than just buying a better set, it's not like these are the only ones in existence, they are not some cool racing specials or anything and some more will turn up etc.
The last option available is that it's better to use what I have and live with it. I can fix the PVs, rebuild the engine and be using the bike while at the same time also search for some better cyls to work with.
In use its considered that it may well be minimally down on power as its so small a scratch but it will still allow some compression to blow by. Taking that to its extent, I guess in use that the walls will wear which would eat away at the scratch over time and so this power loss could possibly see an improvement by being used. im not expecting that really of course, but it is logic I guess haha.
CONCLUSION: As i'm not going to do thousands of kms on these and this is a fun bike for the city (and for me to compare with the same bhp LC350 I have built), I'm thinking that a couple of bhp wont be a huge issue. Sure I'd love these to be perfect, but we are dealing with 35+ year old parts on our bikes so I have to accept some compromise I guess. Rather than mess with these any more I'd be better off finding a better set of cylinders and in the meantime since Ive already spent the time and money on these I may as well run them and see what its like.
So, back to the original job of sorting out the PVs and then time to start it up and see what its like I guess. It is disappointing and no it not ideal, but it is what it is I guess...
I'll keep searching for another set of 51Ls, hopefully some ebayer/gummy will list them incorrectly and I can pick some up cheap hehe. It wasn't that long ago that all 250 cyls were only good as paperweights. Years ago a guy I know offered me a table top full of them (20+ I think) for $100 as they were being taken to the scrap man. sigh, why didnt I buy them?!
...And, yeah Im painfully aware that it's probably my own fault that so many people know what a 51L cylinder is, before I posted about them most had no idea and all 250 cyls were just junk no one could sell. Such is life i guess. If anyone has a set they need shot of then Im all ears of course, but dont want to eat into anyones spares they are planning to use etc.
Finally, a huge thanks again to all who posted and messaged me on this. I really appreciate the support. Love this community! In fact it is what makes this a great hobby. Without you guys there would be no hobby, just hassle.
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251LC
Sept 20, 2021 7:58:28 GMT 1
via mobile
JonW likes this
Post by midlifecrisisrd on Sept 20, 2021 7:58:28 GMT 1
I'd agree with running them but would maybe get the piston/bore clearance checked. Looks like it's been bored too big with no room for honing
Barrels have pick up marks all the time and we don't worry about them. Not like it's on the thrust face either
I've opened engines that were running fine and they've had massive marks from Circlips leaving the building
Steve
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251LC
Sept 20, 2021 9:48:53 GMT 1
Post by JonW on Sept 20, 2021 9:48:53 GMT 1
Thanks Steve, good points, well made.
Ive ordered a bore measure kit and also a hone in case i can use it. We are in lock down for another month so may as well DIY this stuff as it'll be quicker n waiting etc.
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