new member! help me plz lol

[sam venables]

rite first hello to all at tsm, always been into two wheels from push bike to the barely safe ie bog seats to motorcross bikes. had a good selection of toys until sum thief decided pay me a visit! and completley wiped me out urgghh. A few months ago i decided to buy another bike and start riding. i bought a 03 cr 250 which is very clean and although a good runner  it was lil noisy so decided to bite the bullet and get the engine rebuilt, whilst i serviced all other bits like sus linkage bushes, tyres and a good general clean. Had the engine bak, built her all back up and took it on the flat back feild for a very steady bed in and then changed the oil. Everything felt perfect like a new un ha ha. The following weekend me and a friend took the bikes to a track and although his is the same year and bike and is still on the original piston (has not been ridden alot at all!) it just felt alot harder to ride and get along with. The bike was sriking in after first kick everytime and all was well! After getting back that day i was givin her a wash when i noticed sumthing that drained my blood, a hairline fracture running round the back of each cylinder bolt. the ones between cylinder and inlet port. Was suggested it would be ok to weld as it hadnt fractured completely to the seat. but after getting it built back up today with rite torque settings it split again without even starting it up, not immediatley either as i was finishing putting the fairings on i heard a crack and realised wat it was any help would be grateful as i am banging my head on brick wall cheers

[Charles Owens]

Hello, welcome to the site.

Is it cracking at the head or the bolts at the base of the cylinder?

Can you get some pictures of it?

[Coop]

Pictures would definitely help like Charles suggests. What are you torquing the bolts to?

[sam venables]

hi, its cracking at the base of the cylinder, the 2 bolts at back between cylinder and inlet port. the cracks are splitting between bolt hole of cylinder base and and external wall of cylinder. sort of cuttin the corner! lol yeah pic would save hassle but carnt get one up till 2morra. goin to order a new one from honda oem not too bad £210 plus delivery. its killin me cus i just built a track at mine and i aint tried the new 40foot step up yet! when i spoke to the builder of the engine i asked him what torque the cylinder bolts were and he said ya carnt torque as one bolt is in the valve cover, which got me thinking a:could be the reason for crack uneven compression rate and b: how i could torque it myself to which i just welded a socket on a loop ended spanner and scale the torques to each other as it had changed. 29flb was what i was workin with. do you think i will need to change piston aswell to be safe, has only done 5 hours (assuming it is a standard size, will check) ahh the joys of toys lol thanks for replies so quick

[factoryX]

Sounds like your mechanic owes you a cylinder. Was it a shop or a backyard mechanic?

[sam venables]

a bike mechanic, he does as hell of alot of bikes and was reccomended by a few riders. just abit fustrating as i am itching get bak on the bike and test my new backyard track! i want to start racing properly aswel. im not a mechanic myself just a joiner with a mechanical mind. at 200 odd quid i dont think its worth trying to get hold of a decent cylinder and re sleeving, plated it as it would cost just as much as a new oem one, how often do u guys do group buys as my next purchase is a set of mag wheels as ive already bent my hoops 

[SachsGS]

Just to clarify something, you say 03 CR250 which should be case reed induction - maybe some pictures might help. I have encountered this problem myself and cracked cylinder base flanges are very difficult to repair. The two methods of welding possible are TIG and MIG. With TIG does the welder have sufficient room for the torch to access the crack? It might be better to use MIG to do the repair.

It is critical with aluminum that the area to be welded is as clean as possible - two stroke mix residue will screw up any weld.Make sure that a proper weld prep is done,don't worry about cosmetics, and make sure that ALL of the crack is accessible. Make sure that both a pre heat and post heat are done and that the welding may have to be done in stages to prevent cylinder distortion.

Don't be afraid to lay on the material - this is the only way the weld will hold.I suspect the welder did a single (cosmetic) pass with a tig torch and as such will never work.

I once had to repair an IT200 cylinder that had suffered through a number of previous failed attempts. I layed on the weld almost a 1/2" (13 mm) thick and it looked ugly as hell but the repair held. IT200 cylinders are almost unobtainable.

[sam venables]

umm yer not a welder myself or dont pretend to be, thats why i left it to someone who did. or so i thought! have ordered a brand new cylinder, think i kno whats done it aswell. I glanced at the old base gasket which the "mechanic" used and realised he had put it on wrong, upside down! The relocation lugs on the one side of the culinder have a larger hole in the base gasket to accomedate them, and being put on the wrong side the relocation studs had to cut a larger hole the base gasket which didnt allow cylinder to drop enough to seat against the crank casing which cracked the wings off cylinder, ahh!  when i get new cylinder will do it myself! with correct torque settings! had a freind down today on a yz125 so tested a few new jumps but fook me forgot how much ya have to keep a 125 in the pipe or it just bogs ha ha track jumps were too close to each other for it!! bring on the cr 250!!

[TMKIWI]

Bummer mate.

At least you have got to the cause of the problem.
And remember, Not all mechanics are created equal.

[ford832]

Amen to that.If you can't do auto you do heavy duty.If you can't do heavy duty you Industrial.If you can't do industrial you do motorcycle.And,of course,if you can't do any of the above,you do marine.  

[TMKIWI]

I have done abit of all those ford.

So I don't know if that makes me F***en Brilliant or F***en awful.

[ford832]

It mostly means you didn't know any better  At least you have the sense to bail out now-I'm still retarded enough to be stuck in it.