Hi All

So I'm still in the process of getting everything together for the rebuild... I'm not going to muck around and replace this and that. It's all getting done. Bearings, conrod, piston, gears, oil pump, oil return valve, etc. The works...

Anyway, so the question is. The conrod (part no. 1VJ-11651-00, which is supersede by part no. 1VJ-11651-01 according to CMNSL.com) has spacers on each side. I read somewhere (for the life of me, I can't find the thread) on this forum that you can run a wider conrod from a later model XT600. This seems like a great idea as a wider conrod = wider big end bearing = greater reliability in my basic little head.

But then I also remember reading that they had different crank pin diameters?

So what is the engine model which conrod fors the 3AJ or 1VJ motors with the spacers removed?

They changed them on the 3Tb, 10% bigger it works out to I think, the smaller crank pins were on the earlier engines. 34L/55W and the like, it basically just does away with the side spacers. The tkr kits seem fine.

jibber wrote:They changed them on the 3Tb, 10% bigger it works out to I think, the smaller crank pins were on the earlier engines. 34L/55W and the like, it basically just does away with the side spacers. The tkr kits seem fine.

TKRJ kits it seems are very hard to come by. None anywhere for sale. No stockists/importers of TKRJ in New Zealand either.

There's plenty of ProX parts available. Are they any good? - http://www.ebay.com/itm/ProX-Connecting ... 1725726578

$77 US for a Conrod Kit kit seems pretty good, plus free shipping within US. It's also Japanese made, so can't be too bad right?

US $77 for ProX Connecting Rod Kit 03.2600 (Bearing, Rod & Pin)

VS.

US $53.87 (Bearing P/N 93310-635C6-00) + US $82.84 (Rod P/N 3TB-11651-00-00) + US $$62.92 (crank pin P/N 1VJ-11681-00-00) + = $199.63 TOTAL.

richardlw wrote:TKRJ kits it seems are very hard to come by. None anywhere for sale. No stockists/importers of TKRJ in New Zealand either.

That`s a shame, they get good feedback from people who have used them (and raced them).

Over here you cannot buy from the importer (trade only) you have to buy from a retailer.

Mezo.

Not a clue ref Prox, I will look later for the tkr.

From what I gather in mx forums, the ProX Conrad kits are fine. I read nothing bad about them. Maybe I could be the ProX test bed! Haha... They do steel intake & exhaust valves for XT too.

From a KTM forum filled with grouchy buggers!

"You think oem con rod and bearings are made by KTM do you, never mind. Nothing wrong with any of the known brands, ProX, Wossner etc..."

"Woosner , prox , mitaka and vertex are all made in the same factory by one company"

"Nothing wrong with the mitaka con rod kit & pistons ( same as pro x )"

"Having experienced both Wiseco and Wossner in a two stroke, Wossner are far superior"

"If you want to have your crankshaft rebuilt use a Pro x (made in Japan)"



So to sum it up, ProX (which are the exact same as Wossner and Mitaka) are fine in a KTM MX bike, so they'll be fine in my XT!

Useful to know

Pro x is a Wiseco sub-company or is owned by them ect.. They're usually pretty good but are more the "economy " line . I don't think they're the same as Wossner but you never know . Most cam chains are made by Borg Warner no matter who's name is on them . It may be possible to use a Raptor 660 con rod as well but I haven't looked into it closely . If it would work there is a bunch of heavy duty versions made to take a heck of a beating.

Wrist pins are all the same size .

.

My basic thoughts are, with my use of throttle, and the only power upgrade being a 10:1 comp 634cc piston, the conrod should be fine. It'd be the bearing that'd give me problems one day if anything?! I'm not exactly MX thrashing the bike. But hey, what would I know?

I'll tell you in a couple of years how it went!

Couple of follow up questions:
1. When/if a big end bearing fails, there's no real damage that is done to the motor right?
2. Also, when balancing the crank (not something I'll do btw), do you take the counter balance shaft into account too?