Two-stroke specialists?

[Cecil]

My pride and joy is a ’91 Suzuki RGV250. I scoured the country to find one in good condition, it was a Jap import so it was restricted to 45bhp. I found some 2nd hand carbs and SAPC (power valve controller) that a guy in the UK was selling and had those shipped over and bought a set of Arrow pipes for it and had the lot fitted at Colemans Suzuki.

The difference was amazing! I loved my bike, it ran like a dream.

I was planning a road trip in November so I dropped it into Colemans for a routine service. The routine service turned into a full top-end rebuild (new pistons, rings, cylinders, power valves etc). I ended up going with after market power valves from a place called The Tuning Works in the UK because everyone on www.rgv250.co.uk claims they’re better than the factory ones.

Anyway since having it rebuilt it’s been horrible, once I hit about 5K RPM it sort of spits and splutters all the way till 9K RPM and then loses power (the best description I can think of is that it's like driving a car with a manual choke pullled right out and planting your foot). I’ve taken it back into Coleman’s once and they tweaked it and got it a little better down low at the expense of power a 9K+, I’ve dropped it back into them again to look at but I’m wondering if there’s a two stroke specialist KBers could recommend?

No disrespect to Colemans at all, everyone there is awesome. They’re all incredible friendly and helpful and tolerate a picky bastard like me. I think the problem might be that the old two-stroke engine isn’t something they work on terribly often anymore so I’m wondering if I’m better off getting someone who lives and breathes two stroke engines? I don’t fault them at all for not getting it right (yet) and will gladly take my ‘Busa (when/if I get one hehe) to them because their service is top notch

I’m in Auckland so I’d prefer the names of Auckland mechanics but I’d be willing to travel to Hamilton if I had to…

[imdying]

Are the Arrow pipes designed to work with standard porting?

You're not picky, you've probably dropped a lot of money on this rebuild, it isn't unreasonable to want it running correctly.

Top bike the RGV, will rape a IL4 250 easily enough, you'll enjoy it when it's right

[Ixion]

Try Ginger Malloy, if anyone knows two smokers he should.

[Cecil]

Are the Arrow pipes designed to work with standard porting?

Too be honest I'm not that mechanical, I know the basics of how the engine runs but when it comes to stuff like that I'm
What I do know tho is that before the top end was rebuilt it ran mint with the Arrows on there...

[imdying]

What I do know tho is that before the top end was rebuilt it ran mint with the Arrows on there...

That should be a fairly good indicator. Have you asked about on RGV forums for ideas on what to try?

[Ixion]

Two strokes is a black art. To diagnose it yourself you need a black cat, 3cc of mouse blood , a gibbous moon , and a virgin.

Alternatively, try Ginger Malloy.

[ZeroIndex]

just hopping on this thread since I've got a 2-stroke

[Motu]

Walk around the bike widershins 3 times whilst slamming your right hand into forehead repeatedly,slam a size 9 steel toecap into the black cat's arse...and then do something about that bloody virgin.Two bottles of Speights Old Dark sitting on a milk crate and your mind will become receptive to the wiley ways of the 2 stroke.

With it happening at a definate RPM it sounds like a power valve problem.These are electronic I presume,so a back to basics is in order.They should cycle when you turn the key on - try to access the mechanism and see if it cycles from shut to open to shut before it starts.

[Cecil]

Try Ginger Malloy, if anyone knows two smokers he should.

Sounds like I'm off to Huntly then...

[Ixion]

Though porting mismatched to the chambers can show up at a specific rev point. I note that new cylinders were fitted.

Sure it doesn't just need a good bollocking?

Anyway if you want to try something yourself, I agree with Mr Motu, power valves are the logical place to start. Cos I never trust those dadfangled contraptions anyway, and on a two stroke there's not much ELSE that you can fiddle with.

BTW I assume that the carbs were rejetted for the pipes, no chance that in the rebuild they jetted them back to standard ?

[awesker]

They should cycle when you turn the key on - try to access the mechanism and see if it cycles from shut to open to shut before it starts.

My RGV runs mint, and when I turn the key on they only take up the slack and get into position, they dont fully open and close then get into position.

(thats what you were meaning right )

[Cecil]

Though porting mismatched to the chambers can show up at a specific rev point. I note that new cylinders were fitted.

Sure it doesn't just need a good bollocking?

Anyway if you want to try something yourself, I agree with Mr Motu, power valves are the logical place to start. Cos I never trust those dadfangled contraptions anyway, and on a two stroke there's not much ELSE that you can fiddle with.

BTW I assume that the carbs were rejetted for the pipes, no chance that in the rebuild they jetted them back to standard ?

Funny you should mention giving it a good bollocking, when I initially got it back from the rebuild once you got it about 8/9K RPM it and kept it there it ran like a dream, if you dropped below that it coughed and spat until it managed to clear it's throat and hit those revs again.

When I got it back after having Colemans take another look it runs fine 0-9K RPM if you give it hell and slip the clutch away from the lights, but it's not easy to ride like that in Auckland's traffic. If you ride it without giving it hell it's okay from 0-4/5K then it coughs and splutters until 9K and just doesn't go any further.

The carbs came off a bike that has Sugaya pipes and had been jetted for those, I believe they're fairly similar to the Arrows and they seemed to run alright when I initially had them and the pipes fitted.

Anyway I've just faxed off a bunch of info about tuning the bike for the aftermarket powervalves from rgv250.co.uk and Dave Copper Racing (the manufacturer of the valves) so hopefully the boys at Colemans can restore it to it it's former glory otherwise I might be giving Ginger a call.

Thanks for all the suggestions and info so far

[Brian d marge]

So

with the pipes and BEFORE tune up it all worked well

After tune up crapola

So something is right with A the tune up / B the parts fitted ....

Assume the fellas did a good Job then its the power valves ( re fit the originals, or make sure they are set up or working correctly)

them ok

Then its something that happened in the tune up, Piston fitted incorrectly??? Rings ??
Though the rev range u say does...make me wonder about the opening of the valves ...just a thought though

Stephen .

[nsrpaul]

logic says if it was ok before, then something was cocked up in the rebuild

i would be droping it off at colemans and telling em that you will pick it up when sorted and to phone you as soon as its ready

two stroke specialist or not, an rgv is a simple bike to work on, and judging by the parts list, the rebuild cost a bomb

why did it need new cylinders, were the old ones scored? do you still have the old ones, were the ones fitted new or second hand?

does the motor run quiet, long shot but good compression on both cylinders, carbs set correctly, float levels right up the pooper may give some of your sypmtoms, but not all

really does sound like a powervalve thing, are they set up right? they are pretty simple but have been cocked up before, i fixed one a couple of years back that nobody could get to run, and the cables to the valves were the wrong way round!

[Cecil]

yeah I figured it wasn't the parts as it ran sweet before the rebuild.

nsrpaul, you're right, the rebuild cost a small fortune but I love my RGV and it's not like they're easy to come by (in good condition) these days so I coughed up.

Yeah the cylinders were scored and the pistions had gouges in them from the power valves been in the wrong place at the wrong time. All the parts were new, the logic I used was that if I forked out now it shouldn't need major cash spent on it for a few years (fingers crossed!)

I had a rough idea that it might've been the power valves not setup quite right as the problems begin at about the RPM range they kick in. I mentioned that to Colemans today and told the guy that it is suggested you shorten then PV springs by a couple of coils to return the valve to it's standard freedom of operation. The thicker pin on the after market valves compress the spring a bit harder otherwise. - There was a little note in there with them when I bought them but I wasn't sure if they saw it or if it got lost in the packaging peanuts and he seemed to think it was a worthwhile thing to look into as up till now they've been fiddling with the carbs I think.

Shortening PV springs doesn't mean a whole lot to me but I'd be interested if someone in the know could tell me if this might be the problem??

Anyways here's hoping they can nut it out this time If they can't it's no biggy, two strokes seem to be regarded as a tricky beast to work on so I won't think any less of them if it proves to be too much of a challenge - I'll just rock on down to Huntly and get Ginger to work some back magic.