3XV Rev Limiter

[Hendo]

Does the 3XV have a rev limiter? (1991 R model)

I'm in the process of doing some plug chops on my 3XVR and once upto 12,000RPM it hits what I think is a limiter and wont rev past. It sounds like a rev limiter too. Doesn't matter what gear.

The bike has martins pipes, porting, opened up top air box and 4 degree advance key.

Its also running a MPH speedo and posh moto box if it makes any difference?

Thanks.

[scooble]

the only rev limit I am aware of is the speed limit that retards the timing in top gear, however, with the posh box, that should be removed, however, your still left a curve that is deliberately limited in an attempt to keep the whole package down to 45hp, however, with the pipes and minor mods you've probably got a bit more power. Best get a zeel and map it to your setup to get the full potential

[mellorp]

Reving it to 12k I hope you have an SP crank in there. The limiter kicks in at 180kph, or if the ECU thinks the speedo has been disconnected. A zeel will cure any electronic woes, comes with plugs and a pretty good std setting as Borut has a 3XV
IMO you need (an SP crank) decent piston/bore/ring clearance, Martins pipes an SP tune and zeel to get started, or go Sugo or the KrazyKat route, but don't mix and match
Then go the Paul route and turn it into a 4DP.....

[Hendo]

Engine was fully rebuilt by myself with a brand new SP crank around 1000 miles ago. Its running like a beauty and pulls very well indeed!

Im just trying to make sure the fuelling is as close to OK as possible before I take it to a dyno.

At 12,000RPM it sorta sounds like pop,pop,pop,pop like a limter. It actually sounds very good but Im unsure if its meant to do it. It does it in any gear, any speed, clutch in or out etc.

I havnt tried it at a standstill yet though.

[maccas]

12k on the tacho is about 11300 real which is bang on where the speedo limiter usually caps the revs.

Have you trimmed the tab back in the speedo? If so, plug the speedo wires back in to the loom instead of the posh firm box.

See if that cures it? My guess is that the posh firm box isn't working for it to do it in all gears.

Dan

[Warwick]

Yes, if the Posh box is wired in correctly, is working OK, and is the correct box for your bike, it should let the bike rev well past an indicated 12k so there is certainly something amiss there.

As Dan says, trying a modded speedo on the road instead will tell you if the box is at fault. 

 

[Hendo]

Cheers guys.

As I said, I installed a MPH speedo in a few years ago, along with the posh moto box so I've never had to deal with trimming the speedo tabs etc.

The posh box is definately the correct one for my bike, as far as the connections being plug and play go anyways.

Its probably been like this for the last 5 years but I'm only noticing it now, since I now have the ability to bury the needle into the upper range after the porting etc.

I may just leave it to be honest, I like having a MPH speedo and I suppose it'll be good for the engine.

[maccas]

Ah sorry yeah missed the mph speedo bit!

Have you go the circuit board from the old clocks? You could do some tests with that

Dan

[Cruising-Blue]

I'm wondering what sort of rev limits / speeds are being targeted / achieved?  I have a completely standard R, which pulls to an indicated 11,500rpm/12,000rpm, in top gear at approx. 100:1 gearing i.e. an indicated 12,000rpm = approx 120mph, which seems pretty good for a standard road-going 250. Personally, I'm not that comfortable holding it at the red-line for sustained periods, but it could just be that I'm getting old!

[Hendo]

Next Question Guys -

How much oil is too much?

The oil shown in the pictures is probably about an hours running (warm ups, then plug chops). Ive always suspected its running too oily, but I have nothing to compare it to. Pump is set up as per a guide that was on here somewhere (possibly by Malc)?




How oily is everyone elses pipes?!

[Paul]

When it's rich it does that.

[Hendo]

When it's rich it does that.

Thats going to be a whole thread on its own once I have finished my plug chopping  , reading my plugs so far I think I'm going to end up with 250 top and 280 bottom. Probably way over the top but hopefully safe.

Probably a stupid question but can dyno operators 'do' A/F ratios on 2 strokes?

There's a fine oil mist over my number plate, wheel, well everything...

[Paul]

The writings on the wall then.
Take jets and go to a really good dyno chap. Not all know 2 strokes so ask around.

[ybk]

That pipe looks a bit rich. The 2 stroke pump instructions in this thread http://pure2strokespirit.net/forums/index.php?topic=2800.0 I am not sure of, it resulted in a richer mix. Ignition on, full throttle and align the lines is what I'm sticking with.

[Hendo]

That pipe looks a bit rich. The 2 stroke pump instructions in this thread http://pure2strokespirit.net/forums/index.php?topic=2800.0 I am not sure of, it resulted in a richer mix. Ignition on, full throttle and align the lines is what I'm sticking with.

How long have you been running it like that ybk? I might give it a go myself