Bore big(ger) cc bore kit for yam rxs 100?

Marc_Buck · Could Be A Chat Bot Joined: 31 May 2004 Karma :

Do they make bore kits, like a 150cc kit for the yamaha rxs 100, i noticed on a website for all kinds of sports exhausts that there was one for the rxs, does anyone know the site?

Back to the question, do they make bore kits for these?

Thanks.
____________________
94 fzr600r

Kickstart · The Oracle Joined: 04 Feb 2002 Karma :

Hi

Think there are some bits available. The old Yamaha RS125 top end would probably fit.

All the best

Keith
____________________
Traxpics, track day and racing photographs - Bimota Forum - Bike performance / thrust graphs for choosing gearing

DM · Scooby Slapper Joined: 16 Oct 2004 Karma :

Believe it or not, they have 175cc kits available here (Bermuda). That is a serious machine Very Happy

.

Anyhow, the sizes available period for RXS's seem to be 115cc, 135cc and 175cc. There's a guy in my area with a 135 that I attempted to race the other day with my well-tuned 100, but it didn't work out as planned...he decided to swerve amongst the traffic and I wasn't for any of that.

If you plan on getting anything larger than 115cc then I'd strongly recommend frame reinforcements in the form of good welding. Over 90 mph, the bikes tend to speed wobble, and I know of stock swingarms that've been bent from the power under hard acceleration.

binge · Emo Kiddy Joined: 02 Jul 2004 Karma :

And if your gona go for the 175cc kit, then I would think about upgrading your bottom end Razz

...
Otherwise the power of the piston will probably distroy it...

Ben...

Marc_Buck · Could Be A Chat Bot Joined: 31 May 2004 Karma :

I am considering the 135, i would have to upgrade the brakes, as i feel unsafe as it is.

But, if i would have to upgrade things for the 135 i might as well just go for the full 175. what kind of performance would this give?

How would i upgrade the frame?
____________________
94 fzr600r

Gazdaman · I did a trackday!!! Joined: 12 Aug 2004 Karma :

175cc might take you over the 33bhp let alone your 14.6bhp limit.

It should touch 90mph, I wouldn't feel safe doing it though.

Gaz

stevo as b4 · World Chat Champion Joined: 17 Jul 2003 Karma :

Making an RXS100 engine into a big bore 175, will certainely increase power, but its unlikely to be even close to a proper yamaha 175cc unit like the IT175, which is around 22bhp i think?
The torque will increase a fair bit, but i doubt there will be much gain in top end power. Also the RXS crankshaft will not be balanced for a 175cc piston, so it will vibrate more and wear/fail sooner. The old RS125 Yamaha had 14bhp and did about 75mph.
the old DT175MX had 16bhp and IMO i would be suprised if a 175cc RXS would make any more than that.

Marc_Buck · Could Be A Chat Bot Joined: 31 May 2004 Karma :

If i was to increase the power i would only do once i have a restricted access liscence.

so with the 175 cc in, it would make about 25bhp and do 90mph?
____________________
94 fzr600r

DM · Scooby Slapper Joined: 16 Oct 2004 Karma :

Well, I'll tell you exactly what I know. A friend of mine had a Yamaha DT 100 with a 175cc kit on it, back before I was friends with him, and he told me it was hard to keep the front end down, even in 3rd gear. This coming from a guy who keeps a Ducati 748 SS in the UK.

The other 175 I've heard of was on an RXS and was a friend of a friend's. My friend went for a run on it one day, said he got up to 140 kph and the whole bike started to wobble, so he backed off, though there was still a good 10-15 kph left. I remember seeing the bike one night and examining the welding. There were 1/2 inch thick strips of steel reinforcing the swingarm and various bits around the frame to help stiffen everything. Wish I could remember more detail, but this was 6 years ago when my knowledge of bikes was mediocre at best.

I think if you got it tuned properly with a performance exhaust installed, you'd be pushing 25+ hp. My RX-100 can break 75 mph on a flat without too many troubles and faster ones than mine have been known to break 85 mph, though they're tuned to a very high level and have a lightswitch powerband. I'm guessing I have around 15-16 hp, so surely a 175 2-stroke can break 25...?

That having been said, you'd probably be better off with a 135. That's a healthy increase in power and, like binge said, you'd be running the risk of gearbox and/or crank failure with a 175. They're the sort of thing you install on your "play" bike, one you don't have to worry about taking to work on Monday.

Marc_Buck · Could Be A Chat Bot Joined: 31 May 2004 Karma :

DM · Scooby Slapper Joined: 16 Oct 2004 Karma :

That makes two of us. Every time I take the block off for a good polishing I have to make extra sure I don't lose anything or I'll be catching the bus Mad

.

I wish I could give you a bit more info, but those kits are very illegal here (100cc 2-stroke / 150cc 4-stroke limit), so also very rare.

Marc_Buck · Could Be A Chat Bot Joined: 31 May 2004 Karma :

Sorry but if i could just bring this up again as im still interested.....

Or even better any suggestions of what engine/top end i could fit in.
____________________
94 fzr600r

Marc_Buck · Could Be A Chat Bot Joined: 31 May 2004 Karma :

Ive found this will it fit?

https://cgi.ebay.com/ebaymotors/ws/eBayISAPI.dll?ViewItem&rd=1&item=4530014971&category=34284&sspagename=WD2V
____________________
94 fzr600r

Gazdaman · I did a trackday!!! Joined: 12 Aug 2004 Karma :

That's just a piston and rings.

Square peg, round hole...

Or more to the point, Round peg, slightly smaller round hole.

You'd need a re-bore to be able to fit that in, and I doubt there's enough metal there to allow such a rebore, you'd need a whole new top end.

Gaz