GSX1100 Cam Timing

[Anonymous]

I have a GSX1100 with various modifications, it currently puts out 126bhp. Last year I fitted slotted cam sprokets and timed both cams to 108 degs, which I understand is a good timing for "all round" performance. However I am happy to loose a little bottom end if I can gain some to end. Is that possible? If so how much do I need to move the timing? I am running standard cams - currently I can not afford to replace these for performance ones.

[RacingJake]

Try 110 on intake and exhaust, but remmeber to check v-p clearance.
50thou on intake and 75thou on exhaust at the least.

Check them a few times between 2 and 10 degrees before and after TDC. that's where they get close.

My bike with mods like's 111.5 on both.

[Anonymous]

How do you check the clearance?

[RacingJake]

That's easy. After you set intake or exhaust timing with the dial indicator still on the valve retainer just rotate the crank until the degree wheels reads 2 degrees after tdc for the intake and push down the rocker arm with a screwdriver with the flat end of the screwdriver against the non-machine surface of the cam. Check at every degree or two as you work up to 10 degrees, just make sure your not on the compression stroke when your checking v-p clearance. Just watch the dial indicator needle as you turn your degree wheel then stop at the number you want to check it at and push down on the rocker arm. See how much it deflects, 50thou for intake and 75thou for exhaust. On the exhaust do the same but start at 10 degrees before tdc and work back to zero.

You don't need to check them all just one each and the rest should be good to go. Once you do it a few times you'll see it's a piece of cake.

[Anonymous]

RacingJake,

Thanks - that sounds easy enough.
I'll give the 110 degs a go.

[Anonymous]

Can some one please confirm that;
75 thou is 5mm
50 thou 3.5 mm

I've checked my inlet clearances but I only have about 2.8mm with 108 timing before I back off the timing I wanted to check I have not messed up the convertion from inch to mm.

[rosco15]

This is not my strong point. Any machinasts want to confirm this
.075 thou is 1.90mm
.050 thou is 1.27 mm
so 2.8mm gives you .1102 or a mile

[RacingJake]

1mm is equal to .03937 inch, if that helps.

[SqDancerLynn1]

This is not my strong point. Any machinasts want to confirm this
.075 thou is 1.90mm
.050 thou is 1.27 mm
so 2.8mm gives you .1102 or a mile

thats real close 1.28mm & 1.92

[duaneage]

There was a time in the UK when they only had inches, not millimeters. Not anymore.

[Anonymous]

Thanks - bad news is it looks like my maths is poor
Good news is my valve clearance is fine
Why do you keep using inchs in the USA - does anyone else still use them 8O
Seems to me it makes everything much harder :roll:

[SqDancerLynn1]

I have to use my metric tools on my General Motors car :?

[RacingJake]

Well, back in the late 70's we where supposed to go metric on the roads but the BeGee's got all the attention. Must of been all that hair.

[Anonymous]

Square Dancer Lynn, over the years I learned, in a pinch.......

Conversion chart

10 mm = SOL *#$@ outta luck!
11 mm = 7/16
12 mm = SOL *#$@ outta luck!
13 mm = 1/2 in (tight fit)
14 mm = 9/16
15 mm = ?
16 mm = ?
17 mm = 11/16
18 mm = ?
19 mm = 3/4"

kph = mph x 1.6

degrees centigrade = 5/9*degrees F - 32

degree wheels read just degrees - you don't have to convert.

Coffee (morning beverage) = tea (morning beverage)

Ahhh, I feel better now too.

[biker66]

Too bad for you guys that the most common sizes used are 10, 12, 13, 14, 15, 17 and 19 mm