Cam question.

[Mekanix]

Oh......ok.....and just an fyi.....when you measure can lobes......its the base circle (not pointy ) that gives you the lift......two cams can have the same lobe height......and diff valve lift numbers

Thanks, got it.

I didn't have anything to go on besides mine and the manual's lobe height specs for the other bikes.

All I wanted to know was that it would generally "fit" and then find the right numbers.

[Steve]

I have not been following your build, so I don't know if the question has already been raised: which 750 and 1100 cams are you considering?

The reason I ask is that there are 2-valve and 4-valve versions of both sizes.
Because the flow characteristics are rather different for the two types, the shape of the lobes is considerably different.
I'm not sure that the 4-valve cams would work on your 2-valve engine.

Yes, this is in addition to the timing problem caused by the difference in piston phase.

.

[Mekanix]

Hey Steve, There's quite a bit to follow so i don't blame ya.

I was thinking of sticking with the 16 valve type and staying away from the 8 valve.


It is a 4 valve per cylinder engine.

[Steve]

My bad, for sure.

Saw the "400", completely skipped over the "8-valve" AND the pictures.

We never got the 8-valve 400 here in the US, so I kinda forget they were available elsewhere.

.

[Mekanix]

Haha, I fixed that

It's no problem, Still value your input


Just think of it is the middle, err,, left two cylinders of a gsx750

[GregT]

Ah, yes, when I suggested GSXR cams I forgot the center cylinders of a four are in step and the twin not so much...
It is possible to cut and reindex the cams in the correct relation - but the cams are chilled cast iron so present a welding problem...
Some tricky machining to put a spigot through the joint then pin the spigot would also work but $$$ will come into it.
Get it running on the standard 400 cams then look at getting an aftermarket grind done. Picking up a spare set of standard cams would be worth doing too.

[Mekanix]

I've tried to do everything on spare parts and keep the originals.

I do have another set of original cams to play with And maybe a complete engine coming.

its good to have options, for now I'm sure the stock will be fine.

[Spyder]

Have you looked into maybe 450 cams, or aftermarket? I'm kinda loosing the concept of "having" to cam a 400?

Though it would be pretty cool to be able to say "my 400 just smoked a 750". haha!

[Mekanix]

I'm kinda loosing the concept of "having" to cam a 400?

I might have to cam a gs400 with a 78mm bore.

There is a problem with using the 450 cams having to do with the rocker offset.

[rapidray]

I am a dealer for Web Cams & Cam Motion & can get yours welded & reground to your specs. I can even recommend what would work well for yours as far as the grind profiles. Ray.

[Roger P.]

A guy named Mr. Riggs rephased an XS650 camshaft by doing the following:















I don't know how much meat there is on the camshaft you have to work with, but it's a pretty novel way to get the timing you need. Your rephase would be much simpler, since the XS cam was going from 360 degrees to 277 degrees. You would just be moving the lobes 180 degrees. If you needed more peace of mind I suppose you could also weld it, but cast iron is tricky to weld and you need someone with experience to know it won't get screwed up.

[Mekanix]

That's really cool. I never thought about indexing them like that .

[rapidray]

Why in the world would you go to that much trouble & time when there are cam grinders that have been doing this kind of stiff for so long?!!! Ray.

[platinum2]

thays what i said ray, would be real easy to send it off for a custom grind/hard facing job

also, where is the sprocket going to bolt up? just wondering

[Spyder]

Don't know if this helps, but I have my valve cover off of my '83 750T 16v right now
And the 2 inner lobes are 180 degrees of each other. Both exhaust and intake.
I'm not very knowledgeable on such mods yet. Hope it might be useful info for you.