23 replies to this topic

[stuart bowes]

good suggestion thanks

 

in that case though, why not get the 202 for now which is about £60, forget the valve seat work which was the main part of the cost, get a skim (£45) and run it with additive 

 

for now.  not long term for best perfomance, etc

Edited by stuart bowes, 27 January 2022 - 12:53 PM.

[stuart bowes]

in fact that is what i've done, £60 is an easy gamble to be fair

 

at least it's got bigger inlet valves and I'll measure it to work out if skimmed already or how much to have skimmed

 

better than standard, anyway

[Turbo Phil]

The 202 in standard form can barely be considered an upgrade. You’re looking at a couple of hp gain.
With some work they can be made decent. They also have larger chambers than the stock 998 head, so without a skim to correct the volume your compression would be lower.
The standard head can be modified to give good results, but requires bigger valves and a lot of port work to be effective.

Phil.

[stuart bowes]

well exactly, so I get the 202, skim it as mentioned aready, it already has bigger valves, so it's an improvement on the standard head.   later on I can pop it off again, get it worked a bit and sort valve seats for unleaded

 

plus the replaced cams, and per the main point of this thread..  seems like a decent plan to me..

 

maybe I can get an expensive head later but it doesn't seem necessary for now, I just want to improve the carbs chances slightly for now

 

I'll probably smooth out the bores a bit myself if needed, that's pretty straight forward stuff

Edited by stuart bowes, 27 January 2022 - 01:22 PM.

[Turbo Phil]

Yes the 202 has a bigger inlet valve (the exhaust is the same as all other small bore heads) but due to the heavily shrouded chamber shape you don’t see the full flow potential of the bigger valve, hence the minimal gain in hp. Some chamber reshaping yields some decent results.

Phil.

[stuart bowes]

presumably also the skimming will reduce the effect of that shrouding? at least a reduction in depth

 

thanks for the additional info I will certainly bear it in mind

Edited by stuart bowes, 27 January 2022 - 02:54 PM.

[sonscar]

Save up and get it all done together would be my choice.I understand this is not always possible.Steve..

[stuart bowes]

it's not so much the availability of the money it's more a case of doing it in stages to make sure that each step is 'worth' doing if that makes sense

 

like right now we're still doing body work and the engine is kind of a side issue, but I'm getting a few bits in and covering a few bases to make sure some bits are on the shelf ready to go

 

obviously I can't skim it myself, but I can do some work with the dremel to open out the chambers and smooth out the ports and see where that gets us

[stuart bowes]

interesting info here on this topic 

 

http://www.guy-croft...topic.php?t=532

 

and signing this thread off now because it's wandered off topic

 

thanks all