Suzuki GSX-R Motorcycle Forums Gixxer.com banner
61 - 80 of 338 Posts

· Likes to race old junk.
Joined
·
3,011 Posts
Discussion Starter · #62 ·
Update.
I discussed the suggestions made for adding a second idler / tensioner to the Double's coupler with my engine builder and the bike's original builder. They offered valid points on why there should only be a single tensioner.

There should never be a tensioner or idler on the pull or "power" side of the chain. This is engineered in to every type of drive on the market today, from cam chains to drive chains. The power side should have as direct of a line from driven to drive as possible. Besides being totally redundant, a tensioner on the power side would see insane forces acting upon it under full throttle.

Since the front engine (lead engine) will be pulling harder than the rear, the top of the chain will be the "power" side. So the the additional tensioner would have to be as heavy duty as the drives themselves to be done right. Having said that, since the bottom of the chain will still be the slack side, that's where the tensioner needs to be.
The bottom will only have tension on it during deceleration and that force is substantially less than full throttle.

Run a bike on the dyno and watch what the chain does under power. Its totally slack on the bottom and whips up towards the swingarm while the top power side of the chain sucks down the suspension, its pulling so hard. Thats the reason behind putting the tensioner on the bottom.

We will definitely increase the idler gear size to reduce it's speed, heat and wear. Again, we will add a chain lube system.

The 530 chain should be more than adequate for the job. Have you ever seen double side plated 630 chain for top fuel bikes??!!

I appreciate your continued interest and support.

Cheers,
Scott
 

· Premium Member
Joined
·
923 Posts
I concur with the advice of where to place the tensioner. I did mention those high forces on the tension side previously.

Your 530 chain may serve you well for your purposes; several short runs lasting several minutes under load. My charts indicate that 530 chain is getting close to recommended max depending on your horsepower and rpm at the countersprocket. Again I would just measure chain stretch frequently

Not sure why you added chain guides, but I wouldn't restrict the chain movement on tension side. I never put chain guides on any design I've done, with loads far exceeding what you have here.
It may not cause you any issues, but chains will move up and down naturally on the tension side and by restricting that movement, those guides are putting forces on that chain and sprockets you really don't need, and at the least are robbing you of horsepower. I could send you a scan of a engineering design text that outlines this (scan too big to post here).
 

· Likes to race old junk.
Joined
·
3,011 Posts
Discussion Starter · #64 ·
I concur with the advice of where to place the tensioner. I did mention those high forces on the tension side previously.

Your 530 chain may serve you well for your purposes; several short runs lasting several minutes under load. My charts indicate that 530 chain is getting close to recommended max depending on your horsepower and rpm at the countersprocket. Again I would just measure chain stretch frequently

Not sure why you added chain guides, but I wouldn't restrict the chain movement on tension side. I never put chain guides on any design I've done, with loads far exceeding what you have here.
It may not cause you any issues, but chains will move up and down naturally on the tension side and by restricting that movement, those guides are putting forces on that chain and sprockets you really don't need, and at the least are robbing you of horsepower. I could send you a scan of a engineering design text that outlines this (scan too big to post here).
Yes, please email me the scan at [email protected]
Thank you!
 

· Likes to race old junk.
Joined
·
3,011 Posts
Discussion Starter · #67 ·
Update.... Progress has been slow, I was overseas for 4 months in Saudi...my engine guy went through a divorce and I had to wait for him to build a new shop...there were many delays with the new big blocks but I finally recieved them...they are very nice with custom 15:1 JE Pistons, blocks were cut for o-rings...cases can now go out for machining...a new idler with a bigger sprocket will be fabricated...the new body from Air Tech will be shipped this month...lots of new upgrades are planned such as Dyna Tech ignitions, new rear suspension, provisions for adding lead ballast etc.

I didn't get a chance to run at Speed Week in August...I got home in mid July and just wanted to chill for a couple weeks, fixed my fence, worked on the race trailer, spent some time with my wife and dog, took some old bikes to a vintage rally...started getting the big Busa ready for the dyno, couldn't get any oil pressure out of the new 1697cc engine, didn't care for the stress and decided that this was starting to feel like work, cancelled my hotel and sold my entries...the Busa brings me sponsorship money and I wasn't interested in just running my R1 or 600RR.

I took a '75 250 Montesa and a bunch of parts that I'd been collecting and started building a cool vintage flat tracker, I shortened the sub frame, I've got an expansion chamber being built for it, parts have been sent out for painting, front and rear suspension are getting rebuilt...I stuffed a turbo in my '86 1100...drove my KLR to Yellowknife for a northern adventure.

I've just returned to Dubai...the Busa and the Double's engines and coupler are now with my engine builder...I'll miss any September events at Bonneville and the World Finals in October are unlikely. I hope to run something at El Mirage in November. Regardless, I hope that when I return home again that I'll be able to put the engines back in the Double and mount the new body.
 

Attachments

· Likes to race old junk.
Joined
·
3,011 Posts
Discussion Starter · #71 ·
Update...
Only 95 days to go until Speed Week 2011.

We are getting custom top end studs made for the 2 x 1316cc engines and then they are ready for final assembly, wasn't happy with what was available length wise from ARP or APE. We took the easy way out and just painted everything high temp black but left the new big blocks natural, I'll put some clear coat on them to try and protect them from salt corrosion.

The front engine is the "lead engine", it's 14:1 compression and the rear is 13:1, there are also subtle differences in the porting and cam specs. We've raised the compression a full point over how the engines were first built back in the early 90's. Next winter, I may mill the rear engine head to bring them both up to 14:1 and designate the lead engine just from ignition timing but for now I'll go with the designer's original vision.

I think they will look sharp with the new heat shields from Rodriguez!:cheers
 

Attachments

· Likes to race old junk.
Joined
·
3,011 Posts
Discussion Starter · #72 · (Edited)
The new body from Air Tech finally arrived. I was home for April and mocked it up, although it was designed for an electric bike, it sort of fits. There are restrictions on how long the tail section can be, including height and how much of the front wheel is covered etc.

Unfortunately delays in getting the engines and coupler finished, means we won't have time to finish mounting the body and the necessary fiberglass work and fabrication. I'm back in the Middle East working, but there's always next year. We'll just focus on getting the engines and coupler sorted this year and I'll run the first gen front fairing again, no shame in that.

Enzo Ferrari is often quoted as having said that aerodynamics were for people who couldn't build horsepower. I'm planning on having both of them covered.
 

Attachments

· Likes to race old junk.
Joined
·
3,011 Posts
Discussion Starter · #73 ·
We have finalized the re-design of the coupler between the 2 engines. The coupler's idler proved to be a weak link during our shake down passes in 2009. I also wanted the chain to run in an oil bath to ensure adequate lubrication and to carry away the heat.

It was frustrating not being able to wind the bike out before because I knew the idler and chain were coming apart. The Double has run 203mph while idling along at only 7000rpm, I've just kept to the short course...2 miles to get up to speed and timed over the 3rd mile. The bike qualifies for the long course...2 miles to get up to speed and timed over the 3rd, 4th & 5th mile. If the coupler works fine on the short course, I'll move over to the long course and see what this old bike will do...

The new idler has a steel sprocket rather than the previous aluminium in addition to being larger to reduce its speed plus it has a bigger bearing. The tensioner will use an arm, small adjustment travel on one end results in greater travel on the idler end. The new aluminium cover will be CNC'd and use an o-ring for a seal. The webbed fins will help cool the oil. There will also be a sight glass and drain in the cover.

Race Tech is building me a new pair of custom rear shocks.

Tire rule changes prohibit me from running the shaved 18" rubber that I had used previously plus my cool 18" PM wheels. Thanks to my Red R and the classifieds here, I've been able to buy a couple sets of 17" PM Wheels that fit the Double. I bought some new race Bridgestones that are on the approved list and had Nate Jones shave them, he works on tires for 400 mph cars so I trust him.

So far, so good...everything is falling into place.

Cheers,
Scott
 

Attachments

· The other OG
Joined
·
6,332 Posts
yeah, thanks for putting up the info
 

· Likes to race old junk.
Joined
·
3,011 Posts
Discussion Starter · #78 ·
That's an awesome bike. When are you running that thing around here??
Thanks. It's just built for running at the Bonneville Salt Flats in Utah...not much good for anything else...isn't geared for drag racing...doesn't turn very well, so track days at Race City are out too...however it does deliver a pretty good cackle when the 2nd engine lights up.

Speed Week is August 13th-19th.

Should have some more photos soon when the engines are back in the chassis.
 

· Likes to race old junk.
Joined
·
3,011 Posts
Discussion Starter · #79 ·
Another update...

I'm pleased to see the engines finally finished and back in the frame. Lots of cables, wires and hoses still to be hooked up, but it should be making some noise in a few more days. I'm looking forward to seeing Mario's repro carb heat shields mounted. Probably another week or so for the coupler pieces to make it back from the factory.

My builder is leaving on holidays in mid July for the Moto GP, so he has some pressure on him now. I'm still in Saudi for another week but will spend most of July in Algeria..if all goes well, I'll just have to mount the new shaved race tires, bolt the fairing on and load the trailer when I get back to Alberta.:frantic
 

Attachments

61 - 80 of 338 Posts
Top