head work (new big valves) and performance

[rosco15]

I just put 1mm oversize stainless steel valves in my gs1100 4v. Anyone have any guesses or experience on what this will give me in the 1/4 mile. The bike ran 10.11 @128 with completely stock head, cams and an 1166 low compression Wiseco kit.

[sharpy]

1/4 mile

Was that down hill?

[skip]

did you do both the intake and the exhaust? or just the exhaust. I did my head years ago with oversized valves and street /strip port job and picked up 3 mph in the 1/4. the et did not drop alot maybe a tenth or so because i run with a small tire stock chassie and no wheelie bars so the extra power was not utilized till after 100 ft or so and the first 100 ft is a big chunk of the et

[rosco15]

No, that was on a flat dragstrip. The video is on my web page in the video section under Thompson DragRaceway Video section. This is a dragbike with slick and wheelie bar.

I did both intake and exhaust valves. Very little grinding. I want to remove that step near the intake valve and match the boots a little. Nothing special.

[Anonymous]

No, that was on a flat dragstrip. The video is on my web page in the video section under Thompson DragRaceway Video section. This is a dragbike with slick and wheelie bar.

I did both intake and exhaust valves. Very little grinding. I want to remove that step near the intake valve and match the boots a little. Nothing special.

A well tuned gs 1100e with those mods should run low tens with someone that can drive it.
Ill bet you break into the 9s--why not some cams and adjustable cam sprockets to ensure a nice hp gain. and more power at the top end.

My new 1981 honda cmt200 will do the quarter in the 9s also ((minutes i mean ))

[massakins]

Ryan, you may be able to inexpensively increase your power a bit further yet.

If it is a race only engine, take out the base gasket and run without it. This is equivalent to .020" off the head and is easily replaceable. A little compression helps throughout the RPM range. Probably still OK on 93 octane pump gas, too!

Second, try to find a set of GS1150 cams for cheap. These are good for approximately 10% extra lift if memory servews and bolt right in; I think they have a bigger cam bolt though so you'll need to machine or replace your sprockets unless some come with them. And the cams need to be degreed as well so the sprockets should be slotted anyways. These two gains should net you almost 2 tenths anyways.

And if you're already there and $$$ allows, install heavy cylinder studs, copper head gasket (if its a race only engine) and nylon wrist pin buttons. All for reliability. Ride hard!

[rosco15]

I took .010 off the head. I have heavy cylinder studs and nylon wrist pin buttons installed. I've been watching ebay for good 1150 cams cheap, but haven't seen anything. I have web 348 lift and megacycle 355 lift cams in the garage ready to go. I just want to get it into the 9.90's and think with the web or megacycle it will run 9.60-9.70. I think the 9.90 would be more consistent in the 60'. Less tire spin when the track starts to go south. Plus if I can run 132 mph that would put me within 20 mph of the fastest bike. I haven't totally ruled out the cams yet, but i'm more into it to win races and less worried about going fast.

[cbxchris]

If it is a strip only bike go for something in the 375 to 400 lift range and low duration. Personally I like megacycle but have used them all. You will need to either run shortened guides or push the stockers down. Be careful and make sure you have 35 thousandths between head and piston at TDC. Best way to accomplish that is use the proper thickness base gasket and get your pistons exactly flush with the top of the cylinder then use a copper head gasket. I use GSXR o-rings around the studs to prevent oil leaks. It does take some minor mill work. O`ring the cylinders with stainless steel wire. With your 1mm over valves make sure your seats are opened to the maximum. There`s lots of things you can do. Not trying to be a know it just had my share of drag bikes for the last 25 years.

[rosco15]

chris,
What do you mean by "I use GSXR o-rings around the studs to prevent oil leaks." Are you talking about the head or base gasket? I appreciate the input.

[cbxchris]

You can mill the top of the cylinder where the studs come through on the oil galleys. I used the earlier air cooled version GSXR o-rings. There are 2 sizes ...use the larger ones(there are 2 sizes for the early model GSXR oil cooled engines...one is much larger and bigger around the stud for better oil flow). This is how suzuki cured the head leakage often a problem on the GS series. Of course the GSXR runs much higher oil pressure. I`ll have to take a mike and see how deep we milled the cylinder. This is a once for all cure all for oil leaks. We constantly had problems with big street bike engines and especially turbos...looked like harleys after a run. They will not leak anymore after this . Forgot to mention I used copper gaskets unlimited gaskets(accutronics). I often had them make the hole bigger around the studs but also did them myself with a dremel..you just have to be very careful. I always used 43thousandths thick gaskets for head to piston clearance. I hope you are understanding what we did...if not let me know I`ll be gald to try and explain better. I know they now have the outside oiling kits but this is much more pleasing to the eye and it does work...just takes a little time. You will have to measure the outside OD of the o-rings and get a mill ground with a pilot to center with...not expensive at all. Just make sure you do NOT go to deep. I want to say we ran 10 thousandths interference but I`ll have to check. Remember if you do this to include the head gasket when figuring interference fit.