Anybody experienced any problems with the 250cc rev 4?

Youngest son has had one just over a year (2008 model), nothing problematic in particular, change the spark plug regularly helps starting.

He has twice been able to hit the oil sump/drain plug which has resulted in a new plug having to be fitted, the sump guard could be doing with being of thicker grade alloy.

Apart from that no real problems.

Big John

Likewise had mine (2008 model) a little over a year, with no issues at all. My drain plug is well protected by my skidplate, so not sure how one does damage to it. The plug and the hole in the skidplate are not in perfect alignment, so I could imagine the skidplate actually hitting/damaging the plug if off center enough, but not the case on mine.

I've had an 07 & 08 and waiting for my 09. On the 07 I could'nt get the drain bolt out untill I opened the hole in the plate a little, the 08 was fine. No real problems, beta

did a pretty good job with the 4-stroke. I did add a 300 kit to the 08, sweet !

Funny you posted about the 300 upgrade kit. I just got my kit yesterday and was wondering how difficult it was to install. It looks pretty strait forward, but did you have any particular problem during the install? I am still waiting on the aluminum muffler that should be here in a couple weeks so I am just trying to get prepared.

Any advice or suggestions would be greatly appreciated!!

Cheers for the replies.

What general maintenance do you have to do and how hard is it, compared to a 2 stroke?

Cheers.

Valves have to be adjusted every 60hr (ish). To do this you need to rock the engine forward on the bottom engine mounting to get to the valves..... put aside 2-3hr for the job. Engine Oil is every 10hr (there is no separate gearbox oil). Pistons & plugs are about the same life as a 2T.

That is about it really.

Ralph

Pistons & plugs are about the same life as a 2T.

Ralph

Piston life is about the same? That surprises me a little. Strokers have their rings dragged across gaping cylinder ports and as such usually last a lot less. I would expect a 4-bang piston and rings to last a fair bit longer, maybe 3:1?

Graham

Ah.... the old 4T bikes went on an on didn't they. Ask a modern 4T MXer how his maintenace schedule has gone up considerably compared to a 2T!

The big change has been the shape of pistons. 4T pistons have got very low profile and small so that the engines are both shorter and rev a lot higher (bringing more Hp). In doing this the piston has a tendency to tip or wobble in the bore knackering the piston and rings. Luckily none of the 4T trials bikes have the delicate/fragile titanium valve - many of which need replacement after xx hours of racing!

Luckily none of the 4T trials bikes have the delicate/fragile titanium valve - many of which need replacement after xx hours of racing!

The Scorpa 250F has titanium valves. 5 of them, as a matter of fact. Since trials engines don't see the same abuse as the MX bikes, I would imagine that the two worlds don't compare. If they did, then the first of the Montesa 4RT's would be getting pretty ripe for piston replacements about now, and that does not seem to be a problem we are hearing about. Fair assumption that the 4 stroke trials bikes will go a long time.