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what to do, cracked cylinder bridge

5K views 12 replies 5 participants last post by  C-Leigh Racing 
#1 ·
I have a trick national LRD jug that was done by Art himself back in the early 90s, but its lived a long life and on the last rebuild i noticed that what is left of the intake bridges are cracked through including the sleeve. was thinking maybe a bigger 310 sleeve and just leave out the aluminum bridge pieces... but that may cause issues with uneven heating cooling with the intake area not have aluminum to help cool it. so would a 86 style 310 work. or is it time to play taps for this fine piece of TRX history and hp? any ideas what i should do for a resleeve would be appreciated...
 
#4 ·
i tried having one of the welders at work weld it up, but he couldnt really get to the crack, so he stopped after one weld. the weld looks like crap.... so suggestions of where to send it that can weld it up and reshape it, and i guess install the sleeve and match the ports while i'm at it?? the jug has been shaved on the top and the bottom.....
 
#5 ·
i would call around the big name engine guys (ct, neil at c-leigh ect.) usually have no problem with stuff like that you could send it to them and he will sen it back re-sleeved welded and port mached near perfect. i've had to many bad expieriances with local guys around me to trust them anymore iv seen some horrorible jobs by so called pros. also what bore is it at now
 
#6 ·
I got a little trick I can do to one thats cracked where your is.

I'll need to know just where the cracks are located & how wide the intake area has been opened up.

If you want it done, you'll need to use the old model R piston & spacer plate after the mod is complete.
I've done a few over the years, works ok & cost a lot less than a re-sleeve.
Neil
 
#7 ·
I'll send you some pics Neil. the sleeve itself is cracked too, so I think im in for a resleeve regardless. I think maybe this was one of the very early "spacer plate/ long rod" motors. The spacer plate is a different thickness than whats considered the standard today (probably why the bottom of the jug has been machined?). i have been using the 86 pistons, its currently .080 over.

so would it better to go back to stock bore or make a 295 out of it?
 
#8 ·
I'll send you some pics Neil. the sleeve itself is cracked too, so I think im in for a resleeve regardless. I think maybe this was one of the very early "spacer plate/ long rod" motors. The spacer plate is a different thickness than whats considered the standard today (probably why the bottom of the jug has been machined?). i have been using the 86 pistons, its currently .080 over.

so would it better to go back to stock bore or make a 295 out of it?
You could do a 295 if thats what you want.
Send those pics & do a good close up so I can see if my trick will work.

Normally the 4.8mm spacer is to thick when doing the long rod old model R piston mod, a 3mm is used.
If the 86 YZ piston is used, a 2.5mm spacer is needed.
Neil
 
#9 ·
if I remember right the plate is about 3/16" which is ~4.8mm. I was thinking it was 4.5mm, but either way, what would that thickness spacer be used for?? for reference I've had this motor set-up since about 1993
 
#10 ·
I wound up taking a bunch of pics, but not really able to get best shots. i was wrong, both of the bridges have been welded, but one of them is incomplete. the black spot on the left bridge towards the bottom of the weld is actually an area with no aluminum


about 60 photos here, maybe you can find a good view: http://s90.photobucket.com/albums/k244/atv.../cracked%20LRD/

:)
 
#11 ·
Ok, I checked those pics out. Couldnt tell, but has the sleeve itself been welded. Can you give me an idea where the cracks in the sleeve itself are at, like how far down on the bridge are the cracks. The cracks, are they only in those two places, both bridges, not on the sleeve to the side beside the transfers.
I seen you had some pics of the jug upside down showing the sleeve skirt, was that trying to show a pic of the bridge cracks through the Boysene port.
If the sleeve itself is cracked on the sides next to the transfers, only way to fix that is with a resleeve.
Let me know how far down the bridge those cracks are on the sleeve.

Normally when those bridges crack in that place, the sleeve will crack about an 1/8th of an inch down from the top of the intake window.
Best I can tell, looks like my trick will work, just depends on where those sleeve cracks are at.
Neil
 
#12 ·
the aluminum in both bridges is cracked, but the sleeve is only cracked on the left one, about 1/8" down from the window as you said. sleeve was not welded....
 
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