My logic says the big end has to cope with the power the engine makes not the cubic capacity. If a 450 is making 60hp, then the standard 630 big end should be able to cope right up to 60hp. That is unless the single cylinder is massive and the big end has to support the weight and effects of a large reciprocating mass aswell as the power produced.
Because a bike running super lean can have a faster burn (similar to knocking, detonation), which means sharper impulse to the connecting rod with each firing. It's kind of like the differences in gunpowder. Pistol powder burns quickly, rifle powder burns slowly. If you load a pistol cartridge with rifle powder, it goes bang. If you load a rifle cartridge with pistol powder, it goes BANG and flies to pieces in several directions very quickly...
Well Flynn . Have you looked at prices of those bikes used. Its still worth at least 4000 on the used market. My rebuilt is not going to cost me more than 2500 thanks all in with shipping modified bottom end with better rod and forged plus prête Head . So I'm still way ahead of the game and the engine is now billet proof.
Flynn knows what a "couple thou" second hand bike gets you... Not sure I would recommend that over a fresh rebuild from a good shop.
My bike was actually a good bargain, I knew about the cam chain and rocker arm before and sorted it. Complications were caused due to not having anywhere good to work on it and in the head the suspected head gasket was actually just a water leak dripping onto the exhaust headers. That is true to a lesser extent here as well. Supermotos even 10-15 years old regularly go for 2000-2500 British pounds compared to many a road bike that go for under 1000 pounds. Even enduros are slightly more expensive, but anything with supermoto wheels demands a massive premium. But rebuilding engines is not as cheap as people think, add in a couple hundred for things like broken parts, special tools, a rounded bolt head here, a stripped thread there, sealants, lubricants, the proper parts instead of improvisations that can only be bought at a massive premium, etc, the list goes on and on. I speak from experience of smaller jobs but I know an engine rebuild would be that x10.
Well still figuring things out but Im pretty sure to have finally found a solution with the help of HTM in Italy. Will be going with there 630 piston and a Carrillo rod with an off-set grind performed to the crank to make it all work. They also said it a poor design with too short of a rod putting a lot of pressure on that poor bearing. They also pointed out that these engines are really sensitive to oil and that I should have been running the factory recommended 10w50 or some 10w60 not the 10w40 I was using. OH well you pay to learn.
Ive been using Motul 5000 10w40 semi synth and have passed 10000 miles, maybe im just lucky. What do you mean by too short of a rod? Who are HTM Italy?
They're just saying the ratio of stroke to rod length is high, meaning the rod gets loaded at a steeper angle where mechanical advantage means higher bearing loads. I run castrol RS 4T 10w50, anything thinner means more noise.
I don't think I've heard of any other big end failures, but never the less I did have Zip Ty do their crankshaft mod on my 630 to provide better oiling. I've been running 0W-40 in my 310, but heavier 20W-50 Golden Spectro full synthetic in the 630 because of the additives. Per George! All OK so far.
I just cant buy into that. If this were the case,we would be seeing more reports of big end failures. We would also see lots of reports of worn piston skirts and oval cylinder bores. I cant think of any post where people have had a messed up cylinder bore or piston without something loose in the cylinder being the cause. this bike only had 7000 miles on it and i bet the bore and piston still look like new, just look at the pictures of the bore an piston in BenM's thread, his bike supposedly had 7K on it when it failed. My money would be on it being a faulty big end bearing right from the start.
My piston and bore still looked new at 11k miles when I had some new gears and forks put in, but I run it a little rich and I don't run thinner than 10W50. I'm not saying I agree with that shop, I'm just saying that is what they were trying to say.
The manual for my 610 recommends 10w40. I wonder why the different oil grades are recommended for such a similar engine.
Well Spice. Happy to know you've lasted that long. You are using a better quality oil in Motul. Book says 10w50. Il be running 10w60 Amsoil or 15w60 Motul once i get the engine back. Here is the website . Paolo is awesome. He knows his stuff and super helpful. http://www.htmracing.it/cms/index.php?option=com_content&task=view&id=11&Itemid=35&lang=en
Jason, I honestly don't know exactly what they do other than get a lot more oil flow. How and where they machine hasn't been explained, perhaps on purpose but I can't say that for sure. More than likely Tinken was involved with the design changes, but TY Davis will certainly know what is done. Give him a call.
What kind of noise were you initially hearing? I do not hear any banging or grinding...only a small ting from left side of engine. I'm assuming it is the aftermarket exhaust acting up. Possibly a small exhaust leak. If I'm hearing a consistent although mild ting noise should I be concerned?
A pronounce "knock" like noise; that is rpm dependant, that is present under light load or light acceleration and kinda goes away under closed throttle. Rod knock. I posted a video somewhere. I'll see if I can dig it up tomorrow
My 630 with 11k miles is parked and not being ridden. It runs as strong as ever but is making some noise from the lower left side of the engine. Was told it doesn't sound like the crank/rod though. Almost wish I could just sell it as it is and put the $ towards a '17 FE.
I think you can. Not advocating selling a problem, but if you pull that side cover off and all is normal, no bits in oil, RH filter intact, etc. then maybe it's your ears messing with you. Now if you're pretty certain something is up then yeah- look into further.
