H100 newbie looking to go a bit faster!

[DuncCb100]

Hi Guys,
I've had a 1980 H100 for a few years now & only ride it every now & then for fun.

I'm Looking for Info on how to get a little bit more power out of it without going over the top.
I'm not after a 20-30hp racebike engine, just hoping to get it going better than standard.

I have read thru the ESE Works posts but it is all a bit much for what I'm after. Great read for you Racers!

I am aware of the CR80 6 Speed box conversion but not keen on that.

Interested to know if anyone can recommend some basic mods, parts etc.

I'm Thinking Reed Block change, Mild Porting, Maybe a slightly bigger Carb & Expansion Chamber Exhaust.

Any Help would be much appreciated.

Duncan

[speedpro]

If you just want a bit more "go" the standard reed block is fine. If you must do something to it, cut the centre bridge out and install a single big fibre reed petal. A 28mm carb is good fitted to something like an old RD carb rubber boot. Go for compression, say 13.5:1, and change the combustion chamber shape to something proper. You can't go crazy here without changing the ignition as you'll end up with a hole in the piston. I've found that although the transfer ports are pretty ugly they seem to be OK for mild motors without modification. You just set them to a height that works with your application. The exhaust needs to be altered for more blowdown. In the end this is what will hold these motors back. It needs to be raised to whatever level is determined as optimum and widened to 70% of bore, across the chord. The ex port below the tops of the transfer ports can be left alone, and only increase the ex port size at the bore face. Do not extend the increase in size further than about 15mm down the port. Do not touch the port where the pipe bolts on, it's tempting but don't do it. On the intake/piston port side, I've left the original port in the cylinder wall alone but added a further port each side. You need to leave a bit of metal for strength between the ports but the extra ports outside edges should be the same width as the reed valve duct.

The basics done right are good for 20hp with a decent pipe. Make the pipe from scratch, don't waste time trying to modify a pipe from something else.

[Akzle]

do it faggot.

[Grumph]

[QUOTE=Akzle;
do it faggot.[/QUOTE]

I suppose at least it had some relevance to the original question as it is a Honda....But those are not the motor with which to fuck as anyone who's built one will understand.

Speedpro has covered the H100 bases pretty well but personally I'd recommend the good old RD/DT Yamaha 4 petal reed block inserted in a ground out inlet. It'll even give you a performance boost with a stock pipe. Standard they appear to be inlet restricted.

[DuncCb100]

Thanks for the info Speedpro.
It's still running at the moment. I was planning on pulling it down in a few months for a freshen up with a couple of mods.
Will be happy to make my own pipe.
Will just have to get my head around the porting.

[koba]

I run an almost standard MB100 on the road/dirt.
Do the gearbox if you can find one, it transforms the bike in to something MUCH better!

[speedpro]

I run an almost standard MB100 on the road/dirt.
Do the gearbox if you can find one, it transforms the bike in to something MUCH better!

Agreed. I put a 6 speed in my MB100 commuter years ago and it was transformed.

[DuncCb100]

You can see my H100 & Z50 in this thread. Hope it works.

Just read most of your #6 thread Speedpro & nice work you've done there!
Very impressed.

Have been looking for a RD350 Reed Block & Carb Adaptor but yet to find anything.

I thinking I'd like to give the inlet & exhaust ports a tickle as Speedpro has suggested.

I am liking the 3 Window Inlet Port idea, Obviously, It is just a wider port with no increase above or below the standard port timing?

How wide do you recommend for the exhaust port?

6 Speed would be nice. Maybe down the track!!

[speedpro]

Couple of shots of extra ports. You can't go full height like the original, it'll break

[F5 Dave]

Every yam of that era used that block and manifold l guess so dt175 etc will fit the bill.