Performance build - feedback for ideas please

[XS1100_OEM4ME]

Ducks Nuts

If that one is the "Ducks Nuts" then this one is the "Gorilla's Balls"

"The motor is proven bulletproof. Jim Bernard just rode the XS11-based Ron Teson/R.C. Engineering Top Fuel dragster-which uses a stock Yamaha crankshaft and main bearings in its super-charged engine - to a new E.T. record with a 7.57 sec. at 184.95 mph pass at Indianapolis"

I reckon this bike's the ducks nuts for grunt, plus it's still a tractable very rideable machine. It's had a lot of work done to it, but nothing too outrageous or over the top

http://www.youtube.com/watch?v=B6wr-VJZZHY

[Eveready1100]

Did he ride it to the track?
That's a whole different world, OEM

[crazy steve]

"The motor is proven bulletproof. Jim Bernard just rode the XS11-based Ron Teson/R.C. Engineering Top Fuel dragster-which uses a stock Yamaha crankshaft and main bearings in its super-charged engine - to a new E.T. record with a 7.57 sec. at 184.95 mph pass at Indianapolis"

While impressive in it's day, that bike couldn't even qualify for Pro Stock Bike these days (which don't run nitro or blowers!), much less a fuel field...

If you really want to go fast, my brother-in-law has his outlaw turbo Suzuki dragbike for sale... mid-sixes at 190 mph+ if you've got the 'balls'....

[turbo2]

For what it's worth, I run a 1196 kit (74.5 mm pistons), ported head, mikuni 33's smoothbores and megacycle hot street cams with shims below. Best ET 10.04 (which was in 1985) although it has to be mentioned that the motor is in a moto-martin frame and have magnesium wheels which all is considerably lighter than the stock XS1100.

There is a fairbit to be gained by filing on the head especially around the valve seats and guides, seem to recall I saw a 33% increase in flow. What I understand from people in the know, the XS1100 head is the best 8v in line 4 cylinder from Nippon.

Im about to fit a milder set of cams from webcam to get more power below 4000rpm and make the bike easier and faster on the road.

The block and crankshaft are very strong in the XS1100, to my mind weak links are the rods + bolts. Also as the gear box is not exactly superfast/smooth it is easy to miss a gear hence imo a rev limiter is a must.

[old_skool]

And....stay away from the ebay carb builders, personally known a few to never return
not mine, but a few buddies tried it.

[petejw]

If you look at my signature, you can see I have a '78 that I'm working on. There is one member here who has some hand written notes from the late 70's, and they show what needs to be done with the cases to get an extra 5 HP! I DO plan on trying to find these, and I will share when I get them.

hi ray,
is this is what ur after?
about half way down the page.


http://www.benefiscal.co.uk/forum/in...?topic=6682.15

[ViperRon]

Heads

Be careful with any changes to the head. I had a cousin that had a very expensive system and years experience doing the polishing and porting on my head. He did it as payback for the help I give building his garage. I would not have spent the money it cost's to get it done professionally. He also explained that the heads were quite well tuned and without the right equipment you could cause performance loss.

I agree with everyone here about tuning carbs there is no way I see of tuning them off the bike.

[XS1100_OEM4ME]

Port polish

+1 on head mods. I have to say, as low tech as the motors are (2 valves per cyl. low rpm limit etc) the heads are amazingly well ported for these bikes. I have done some port polish and CC work back in the day on auto racing heads where you could get good gains from factory, but these heads could go the other way pretty easy if you start removing mat. and changing the air flow. I guess it is because one thing Yamaha is very good at is tunning stuff, like the OEM exaust, the heads work great right out of the box That must be why Lexus had Yamaha tune the exaust on there new quarter million dollar sports car

Be careful with any changes to the head. I had a cousin that had a very expensive system and years experience doing the polishing and porting on my head. He did it as payback for the help I give building his garage. I would not have spent the money it cost's to get it done professionally. He also explained that the heads were quite well tuned and without the right equipment you could cause performance loss.

I agree with everyone here about tuning carbs there is no way I see of tuning them off the bike.