This is what we saw after the 2nd run. The chain was pretty much welded together, it must have taken alot of power to turn it. With the idler removed, you can see that there is a machined slot for it to rest in, which gives us adjustment travel. The idler mount with its bottom adjuster is quite solid. When the coupler's cover is mounted, a bolt goes from the cover and through the idler to the back of the coupler plate. So with all this, I 'd say it is triangulated. I think the design flaw was the aluminum sprocket and the lack of some sort of chain oiler. I've looked at Scott Oilers but picked up something off ebay for a go-kart, I'll modify it to dump a quart over 5 miles.
I appreciate your comments, its always good to have someone else's opinion on a solution.
I can't wait to ride the Double again. Its fun just starting it!
I'm in the middle of a desert some where in sunny Saudi Arabia right now....
Both engines are out of the bike now. Carolina Cycle should be shipping my new big blocks and pistons early next week. I have to farm out more and more all the time because I'm never home. My engine builder needs to finish stripping the engines, then the cases can be bored for the bigger sleeves. I'll certainly post some pictures once we start stacking the engines, they will both be 1316cc, 15:1 compression. I'm going to install a couple of Dyna 2000 ignitions as well.
Hopefully the modified coupler will hold things together, if not, we'll try another idea. I want to run the bike again this year with the GSXR fairing. If the drive train issues are solved, its getting a very slippery body next year.
BR, I have been looking at this coupler chain(fried) and have to wonder if both engines are synched up well. If both engine were 100% equal thoughout the RPM range, I dont think this chain would look like that, I wonder if one engine is carrying more load than the other.
Just a thought
With that set up, I don't think both motors can ever be in perfect synch, well for very long anyway. One will always be pulling the other; just too many variables that would drive them to be out of sync (think about the horsepower difference at any rpm between any two engines not matter how well matched). Mechanical systems would just rely on some sort of slip or over run clutch to account for the differences between the two engines. Computer control measuring output shaft rpm or some other variables would be the only way to match two engines direct coupled that way.
I am sure you are pushing the limits of that 530 chain anyway. A chain oiler may work well for you for your needs on short runs, but you may find you will need to step up to higher load chain or dual row perhaps.
With multiple engines, there is actually always a lead engine. This can be accomplished by simply changing the timing by a couple of degrees on one. As mentioned earlier, the bike was built in the early 90's and we have been trying to understand some of the reasoning behind the builder's decisions...most of them have been really well thought out. Upon tearing down the top ends, we learned that the cam specs were a little different between the engines, one head had light porting, the other was extrude honed...just little differences between the two. With the new overhaul, I'm trying to bring them a little closer. I agree, they seem to be out of synch. We've spent alot of time playing with the throttle cables. I know they are both wide open at full throttle, the problem is the bike has never seen full throttle...lots of wheel spin at anything over 3/4 throttle. 203mph at only 7 grand!! If it was easy, everybody would build this shit.
I still believe the coupler's idler was a weak design and the plan was to just lube the chain before each run. I'll see if I have a picture of the updated coupler and the new upper chain guide. I'm going to install a chain lube system as well, its going to make a mess but hopefully it will help. I've only run the bike on the short course, its got a long way to go before I trust it on the long course. I plan on retiring my Busa this year, the Double is way more fun!!
This is the current coupler set up. I went with a 530 oring chain, it was a non-oring chain before, it should retain some of the lube. The idler sprocket is now steel, the old one was aluminium and it got loose on the bearing after we baked it a few times. Again, I'll add some sort of chain lube system.
All we can do is try and hopefully move forwards. I appreciate your suggestions.
I think it looks good, give it a whirl. If you have some sort of cover over the coupler, you may want to try gasketing it, or sealing it with silicone to keep oil in and salt out. Keep us informed on how it works out and good luck!
Have you ever dynoed your engines? Do you check chain stretch between runs? That may give you early warning if you are exceeding the limits of that 530 chain, especially if you are going greater than your previous max of 3/4 throttle.