And so it begins.......... Mk2 rebuild
Posted: 30 Aug 2011, 21:36
Those of you that have seen my 'newbie' post will know that I've just bought a Mk2 CRM 250 in bits!! Not ideal for everyone but I like doing things the hard way!!
This is the first bike I'll have rebuilt, so there will undoubtedly be some head scratching and newbie questions asked. Hopefully I'll have a bit of a chance as I'm an electrical engineer by trade with access to a fairly well kitted out workshop, and have tinkered with cars since I passed my test.
So, to the bike, it's a white Mk2, '91, imported into UK in '98. The guy I bought it from seemed like a genuine guy, interested in bikes, spoke a lot about older 2 strokes, and said he had rebuilt a couple of KH250's. He had bought this for greenlaning but found that the swingarm bearings were nackered. Sounds like he had fun getting the swingarm spindle/bolt out, but it is out. He then carried on stripping the bike, but lost interest/time.
Looks like it's pretty much all there, no doubt there are some fixings and small bits lost, but definitely the bulk is there. He hasn't stripped it quite as methodically as I would have done, but I can see some of his logic!!
So from a quick look over my intial plans are as follows:
- frame to be shotblasted & powder coated satin black, considered getting swingarm one the same but thought it might be a waste as it would get scuffed/chipped and soon look tatty - thoughts?
- service shock & forks, forks feel pretty soft at the moment. Are there any common mods to the internals to make them a little better, or is it a case of trying heavier oil or different oil levels?
The fork uppers have unfortunately been painted gold (I'm guessing that the original anodising was tatty), but this just gets scraped where the yokes are fitted/adjusted. I plan to strip the paint off, if the anodising is poor I'll consider getting them re-anodised. Has anyone had this done? Pricey?
- rebuild engine as necessary.............
- generally tidy as I go, replacing any bushes/bearings as necessary
- Pass my test and take it for a spin!!
So, how do you get a CRM in the back of a Volvo? Like this:
[url=http://www.flickr.com/photos/25266351@N06/6097306941/][img]http://farm7.static.flickr.com/6205/609 ... 09cd_b.jpg[/img][/url]
[url=http://www.flickr.com/photos/25266351@N06/6097306941/]IMG_20110827_110330[/url] by [url=http://www.flickr.com/people/25266351@N06/]Hallsy01[/url], on Flickr
He was nice enough to let me have the boxes!!
So, had a better look at the engine. Seller had removed the barrel from the crankcase, and it looked to be in OK condition, but the head was still on so couldn't see properly. Back in the workshop I could see why head was on. Even though all the nuts were removed, one stud had bitten into the head and wouldn't come off. The thread on the stud had been mauled as well. Welded a nut on and removed stud. There are a few marks in the squish area, from debri I'm guessing (sorry for poor pic quality, I only had my phone cam at work):
[url=http://www.flickr.com/photos/25266351@N06/6097855556/][img]http://farm7.static.flickr.com/6010/609 ... 40d0_b.jpg[/img][/url]
[url=http://www.flickr.com/photos/25266351@N06/6097855556/]IMG_20110828_123124[/url] by [url=http://www.flickr.com/people/25266351@N06/]Hallsy01[/url], on Flickr
Here is the piston as removed:
Fairly normal carbon pattern?
[url=http://www.flickr.com/photos/25266351@N06/6097307733/][img]http://farm7.static.flickr.com/6132/609 ... be9b_b.jpg[/img][/url]
[url=http://www.flickr.com/photos/25266351@N06/6097307733/]IMG_20110828_120649[/url] by [url=http://www.flickr.com/people/25266351@N06/]Hallsy01[/url], on Flickr
Intake side:
[url=http://www.flickr.com/photos/25266351@N06/6097854128/][img]http://farm7.static.flickr.com/6197/609 ... fb12_b.jpg[/img][/url]
[url=http://www.flickr.com/photos/25266351@N06/6097854128/]IMG_20110828_120700[/url] by [url=http://www.flickr.com/people/25266351@N06/]Hallsy01[/url], on Flickr
Exhaust side:
[url=http://www.flickr.com/photos/25266351@N06/6097854912/][img]http://farm7.static.flickr.com/6195/609 ... 3c07_b.jpg[/img][/url]
[url=http://www.flickr.com/photos/25266351@N06/6097854912/]IMG_20110828_120718[/url] by [url=http://www.flickr.com/people/25266351@N06/]Hallsy01[/url], on Flickr
Most of the barrel looked to be in OK condition and is still on original bore (66.0mm), but just above the exhaust port you can see and feel some marks:
[url=http://www.flickr.com/photos/25266351@N06/6097306207/][img]http://farm7.static.flickr.com/6121/609 ... e47f_b.jpg[/img][/url]
[url=http://www.flickr.com/photos/25266351@N06/6097306207/]IMG_20110828_123359[/url] by [url=http://www.flickr.com/people/25266351@N06/]Hallsy01[/url], on Flickr
[url=http://www.flickr.com/photos/25266351@N06/6097850992/][img]http://farm7.static.flickr.com/6192/609 ... d96f_b.jpg[/img][/url]
[url=http://www.flickr.com/photos/25266351@N06/6097850992/]IMG_20110828_123339[/url] by [url=http://www.flickr.com/people/25266351@N06/]Hallsy01[/url], on Flickr
[url=http://www.flickr.com/photos/25266351@N06/6097304793/][img]http://farm7.static.flickr.com/6006/609 ... a88e_b.jpg[/img][/url]
[url=http://www.flickr.com/photos/25266351@N06/6097304793/]IMG_20110828_123326[/url] by [url=http://www.flickr.com/people/25266351@N06/]Hallsy01[/url], on Flickr
[url=http://www.flickr.com/photos/25266351@N06/6097304091/][img]http://farm7.static.flickr.com/6068/609 ... 15c2_b.jpg[/img][/url]
[url=http://www.flickr.com/photos/25266351@N06/6097304091/]IMG_20110828_123255[/url] by [url=http://www.flickr.com/people/25266351@N06/]Hallsy01[/url], on Flickr
So, looks like it will need a rebore. I'll get a borrow a bore micrometer tomorrow and see if I can meaure the bore around the damaged area to get an idea of how much it will need taking off.
In the meantime, I have had a very quick look at the bottom end. The crank feels smooth by hand, but what is a concern for me is that the conrod can be rocked from side to side. I understand this can be normal, but how much is too much, if any? Likewise, does anyone know the specs for side to side movement (not rocking), I only have the Leisure Trail manual at the moment. Pulling the conrod up & down when at TDC I can't feel any knocking that would suggest radial wear, but the rocking seems to suggets otherwise. As this is a needle roller bearing rather than shells, is that what causes the slight wobble, or a sure sign the big end is nackered? The big end bearing doesn't look discoloured at all.
I understand the original mk2 workshop manual is all in Japanese, is the AR manual a worthwile download or will very little be the same?
This is the first bike I'll have rebuilt, so there will undoubtedly be some head scratching and newbie questions asked. Hopefully I'll have a bit of a chance as I'm an electrical engineer by trade with access to a fairly well kitted out workshop, and have tinkered with cars since I passed my test.
So, to the bike, it's a white Mk2, '91, imported into UK in '98. The guy I bought it from seemed like a genuine guy, interested in bikes, spoke a lot about older 2 strokes, and said he had rebuilt a couple of KH250's. He had bought this for greenlaning but found that the swingarm bearings were nackered. Sounds like he had fun getting the swingarm spindle/bolt out, but it is out. He then carried on stripping the bike, but lost interest/time.
Looks like it's pretty much all there, no doubt there are some fixings and small bits lost, but definitely the bulk is there. He hasn't stripped it quite as methodically as I would have done, but I can see some of his logic!!
So from a quick look over my intial plans are as follows:
- frame to be shotblasted & powder coated satin black, considered getting swingarm one the same but thought it might be a waste as it would get scuffed/chipped and soon look tatty - thoughts?
- service shock & forks, forks feel pretty soft at the moment. Are there any common mods to the internals to make them a little better, or is it a case of trying heavier oil or different oil levels?
The fork uppers have unfortunately been painted gold (I'm guessing that the original anodising was tatty), but this just gets scraped where the yokes are fitted/adjusted. I plan to strip the paint off, if the anodising is poor I'll consider getting them re-anodised. Has anyone had this done? Pricey?
- rebuild engine as necessary.............
- generally tidy as I go, replacing any bushes/bearings as necessary
- Pass my test and take it for a spin!!
So, how do you get a CRM in the back of a Volvo? Like this:
[url=http://www.flickr.com/photos/25266351@N06/6097306941/][img]http://farm7.static.flickr.com/6205/609 ... 09cd_b.jpg[/img][/url]
[url=http://www.flickr.com/photos/25266351@N06/6097306941/]IMG_20110827_110330[/url] by [url=http://www.flickr.com/people/25266351@N06/]Hallsy01[/url], on Flickr
He was nice enough to let me have the boxes!!
So, had a better look at the engine. Seller had removed the barrel from the crankcase, and it looked to be in OK condition, but the head was still on so couldn't see properly. Back in the workshop I could see why head was on. Even though all the nuts were removed, one stud had bitten into the head and wouldn't come off. The thread on the stud had been mauled as well. Welded a nut on and removed stud. There are a few marks in the squish area, from debri I'm guessing (sorry for poor pic quality, I only had my phone cam at work):
[url=http://www.flickr.com/photos/25266351@N06/6097855556/][img]http://farm7.static.flickr.com/6010/609 ... 40d0_b.jpg[/img][/url]
[url=http://www.flickr.com/photos/25266351@N06/6097855556/]IMG_20110828_123124[/url] by [url=http://www.flickr.com/people/25266351@N06/]Hallsy01[/url], on Flickr
Here is the piston as removed:
Fairly normal carbon pattern?
[url=http://www.flickr.com/photos/25266351@N06/6097307733/][img]http://farm7.static.flickr.com/6132/609 ... be9b_b.jpg[/img][/url]
[url=http://www.flickr.com/photos/25266351@N06/6097307733/]IMG_20110828_120649[/url] by [url=http://www.flickr.com/people/25266351@N06/]Hallsy01[/url], on Flickr
Intake side:
[url=http://www.flickr.com/photos/25266351@N06/6097854128/][img]http://farm7.static.flickr.com/6197/609 ... fb12_b.jpg[/img][/url]
[url=http://www.flickr.com/photos/25266351@N06/6097854128/]IMG_20110828_120700[/url] by [url=http://www.flickr.com/people/25266351@N06/]Hallsy01[/url], on Flickr
Exhaust side:
[url=http://www.flickr.com/photos/25266351@N06/6097854912/][img]http://farm7.static.flickr.com/6195/609 ... 3c07_b.jpg[/img][/url]
[url=http://www.flickr.com/photos/25266351@N06/6097854912/]IMG_20110828_120718[/url] by [url=http://www.flickr.com/people/25266351@N06/]Hallsy01[/url], on Flickr
Most of the barrel looked to be in OK condition and is still on original bore (66.0mm), but just above the exhaust port you can see and feel some marks:
[url=http://www.flickr.com/photos/25266351@N06/6097306207/][img]http://farm7.static.flickr.com/6121/609 ... e47f_b.jpg[/img][/url]
[url=http://www.flickr.com/photos/25266351@N06/6097306207/]IMG_20110828_123359[/url] by [url=http://www.flickr.com/people/25266351@N06/]Hallsy01[/url], on Flickr
[url=http://www.flickr.com/photos/25266351@N06/6097850992/][img]http://farm7.static.flickr.com/6192/609 ... d96f_b.jpg[/img][/url]
[url=http://www.flickr.com/photos/25266351@N06/6097850992/]IMG_20110828_123339[/url] by [url=http://www.flickr.com/people/25266351@N06/]Hallsy01[/url], on Flickr
[url=http://www.flickr.com/photos/25266351@N06/6097304793/][img]http://farm7.static.flickr.com/6006/609 ... a88e_b.jpg[/img][/url]
[url=http://www.flickr.com/photos/25266351@N06/6097304793/]IMG_20110828_123326[/url] by [url=http://www.flickr.com/people/25266351@N06/]Hallsy01[/url], on Flickr
[url=http://www.flickr.com/photos/25266351@N06/6097304091/][img]http://farm7.static.flickr.com/6068/609 ... 15c2_b.jpg[/img][/url]
[url=http://www.flickr.com/photos/25266351@N06/6097304091/]IMG_20110828_123255[/url] by [url=http://www.flickr.com/people/25266351@N06/]Hallsy01[/url], on Flickr
So, looks like it will need a rebore. I'll get a borrow a bore micrometer tomorrow and see if I can meaure the bore around the damaged area to get an idea of how much it will need taking off.
In the meantime, I have had a very quick look at the bottom end. The crank feels smooth by hand, but what is a concern for me is that the conrod can be rocked from side to side. I understand this can be normal, but how much is too much, if any? Likewise, does anyone know the specs for side to side movement (not rocking), I only have the Leisure Trail manual at the moment. Pulling the conrod up & down when at TDC I can't feel any knocking that would suggest radial wear, but the rocking seems to suggets otherwise. As this is a needle roller bearing rather than shells, is that what causes the slight wobble, or a sure sign the big end is nackered? The big end bearing doesn't look discoloured at all.
I understand the original mk2 workshop manual is all in Japanese, is the AR manual a worthwile download or will very little be the same?