posted
im checkin this out for a friend. he seems to constantly bust his conrods on his RB engines, and i think its related to the head clearance.
wut is the head clearance for .12s, .15s, and .21s (Nitro % wise). how do u know how many shims to add when u go up on nitro? add one .1mm shim every 5% nitro u go up?
he just busted a C12, but before that an X15. hes running Trinity 25% and said hes "adding shims" (he said he added 2, but didn't say wut size).
what is causing him to bust his conrods/big pin so much?
[ 30.08.2002, 16:02: Message edited by: Joe Arena ]
Posts: 78 | From: Freehold, New Jersey | Registered: Jul 2002
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posted
well, do u have any idea why hes busting conrods? hes messed up an X15 along with his recent C12. thats the main reason i posted this, i thought that the head clearance would be involved in some way or another.
ps: i apologize if im repeating too many questions, im still new here though i wanna thank you for helping me regardless.
[ 30.08.2002, 16:03: Message edited by: Joe Arena ]
Posts: 78 | From: Freehold, New Jersey | Registered: Jul 2002
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posted
Sounds to me like an over-rev situation, or maybe getting on it too hard while cold and tight! I have never lost a conrod on a Novarossi or RB engine , even in a runaway situation (only had 1 or 2 in last 10 years). The conrods do wear out, especially at race tune with low oil fuels. If you ever hear a "pinging" coming from the head , it's likely the bushing is worn.
Posts: 15 | From: Weatherford, Tx. USA | Registered: Jul 2002
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David Root
unregistered
posted
Only a couple of things can bust the rod. Unmercifully over revving the engine is the #1 reason I can think of. Especially if it is the same person.
A worn crank will help the rod break too. The big end gets oval shaped, then the rod is loose and can break easier.
posted
he says his temps have been under 210....just to let u know.
what about running too lean? the prob is, i would expect higher temps if lean....
Posts: 78 | From: Freehold, New Jersey | Registered: Jul 2002
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posted
If the engine has been run under 210 it seems hard to believe to have a conrod problem, are your sure there is no problem with the reading of the temperature?
posted
i highly doubt that hes takin the temp wrong....but then again im not there to see it.
he keeps blaming it on the fact that the bushing is too tight. what he is talkin about, i have no idea? but i find it hard to believe hes had two RB motors that were defective....
Posts: 78 | From: Freehold, New Jersey | Registered: Jul 2002
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posted
The fits of the conrods are O.K., we are using the engine ourselves and if there are any problems in this direction we would recognize them... In this case looks more like an overrev situation or simply running the engine too lean.
posted
Ask your friend to make sure the conrod's oiling hole and piston cutaway are pointing towards the crankshaft and the new pin is securely fastened by new clips.
Posts: 22 | From: Tokyo | Registered: Aug 2002
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UBBFriend: Email this page to someone!
![[Frown]](frown.gif)
though i wanna thank you for helping me regardless.
