Top end rebuild, advice needed?

4 replies to this topic
  • Stranglersfan

Posted September 30, 2005 - 01:08 PM


I stripped the top end down today to try and find my "Hissing" problem (discussed elsewhere on the forums) and was wondering if i can just throw it back together using the stripped parts? but first i need to ask you guys for advice on how to ascertain (hopefully by looking at the pics?) http://www.strangler...426Cylinder.jpg
If i need a new piston kit/rebore or do these parts look ok to put back in? I don't see any score marks or gouges on the cylinder but there does appear to be a "shadow" at TDC, now whether this is more than just a shadow is yet to be confirmed when i have a closer inspection of it tomorrow, i was late finishing in the garage so by the time I'd stripped it, i had time to take some pics and then had to get cleaned up, (the missus can be a pain at times!).
Anyway, it looks to me like the bore is relatively ok as i can still see the honing marks and since they are not "polished" off, i am presuming that it is still in fairly good condition and does not need a rebore, am i correct in thinking this? This being my first ever strip of a WR I'm learning as i go along, but i know from having built several Car engines in the past, honing marks on the bore was a good thing when rebuilding as it help "bed" the rings. What do you guys think? should i just put it all back together and hope the "hissing" sound (like escaping gases when on compression) is either a faulty head gasket (but no oil in the water or bubbling?) or i have a burnt valve (my first conclusion?) as i say, this problem is explained elsewhere on the forums because i was concerned when doin my valve re-shim how i could go past TDC without having to use the de-compression lever when on the compression stroke indicating an air leak of some description?
One more thing. there appears to be "burn" marks on the crank (see pic)
Has anyone got ideas about these and what would cause that?
last thing, what is the best way to check the piston/bore/pin etc to see if they are ok to go back in as they are? A compression ring in the cylinder at different intervals to check gap, or is there a better way? feelers down the side of the piston (minus rings) while it is in the bore? haven't come across any of this info in the manual, unless I've missed it?
Obviously I'd like to go "The Full Monty" and have a 444cc kit and auto-cam, but for now as finances are very low I'd like to get her fixed for minimal cost if at all possible?
Anyone got any tips for a dropped circlip down below the crank? i hope it's on the floor somewhere and not down there in the darkest depths of "cogland"? :applause: I'd hate to think my "top end overhaul" turned out to be a complete stripdown! :lol:

Thanks for any help and advice guys, great source of info these forums :banghead:

  • Pincushion

Posted September 30, 2005 - 03:30 PM


how was the compression before you tore it down? It visually looks okay (no obvious trauma to the cylinder or piston), but that doesn't mean much since the tolerances are so tight on these motors. At the very least replace the rings, reassemble and perform a leak-down test.

Get a long handled magnet and a flashlight to get the circlip out.

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  • Brettv

Posted September 30, 2005 - 05:09 PM


the burn marks on the crank are normal from the factory

  • slipper40

Posted October 17, 2005 - 03:20 PM


I have just completed a full rebuild and your bore looks just like mine and that,s well within spec, i would slap new rings on take the valves out and clean the carbon off (this may be the cause of your hissing noise?) lap the valves in and re set the clearances

  • Indy_WR450

Posted October 17, 2005 - 04:02 PM


I agree with the members above. Your piston and jug look good. If you want to save money just put new rings in her. The top of your piston looks very good for a 426. :banghead:

The head and valves should be rebuilt or replaced for sure. It is time. :banghead:


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