New bikes

[longmoreuk]

Just got back form the bike show. Lucky enough to get on the trials bikes and the Yamaha off road experience. I loved both. Had a rip on the Yamaha wr250. Now- my question is should my bike (Crm) feel as quick as one of those? I have been sensing that my crm is underpowered but really had no idea. The wr250 was a beast though, loved it. It was a 4 stroke so I thought my Crm should give it a kicking but didn't. Am I just expecting too much from the old gal? And if so, what's the best thing I can do to get it flying. I could read the faq's again but would rather here peoples experiences.

[andrew19]

I've been toying with getting a WR250 but not found one in my neck of the woods yet. I want an electric start. Unfortunately I've not ridden one so can't comment on comparison with CRM. If one believes the figures the CRM should be more powerful....

[mudboots]

If you love the two strokes how about Gas Gas EC 300 or Beta RR 300, TM 300 or Husqvarna I am looking at buying a Beta RR 300 for here in Australia next year if I could I would have it sent to Thailand but that's a sad story for imports.
But on the bright side I have my Crm 250 MK1 there road Geg'd

[fishtail]

interesting thread.. a friend of mine has a WR - maybe I will ask im for a spin on it-

isnt the WR a heavy beast tho?

electric start sounds nice tho

[knackeredMk1]

All the 250 four stroke enduros will be much better suspended than the CRM and lighter feeling. The actual power is a little less, particularly at the revs the CRM is best at. The four strokes rev much higher though so feel faster.

[longmoreuk]

It was heavy yes - but not too bad. I have v short legs so was hanging off it to start with but managed to hold it up ok when someone decided to stall in front of me and I hit his wheel which proves its manageable. I am not actually sure it felt lighter than my crm but might well have been. The WR felt a lot faster though. I will say however, the crm has only been on road with me, off road it might feel v different. I absolutely loved it so need to find some places to go, I was getting well into it after 15 minutes on the dirt! I want to do some endure stuff though, motocross tracks put the fear of god in me, I want to do stuff at my own pace and build up.

Did you mean the four strokes rev lower but have more torque? ie a diesel compared to petrol engine. a two stroke revs much higher than a 4 stroke doesn't it.

I also had a go on a gas gas trials bike at the ACU try trials stand, that was awesome, would like to have a go at trials some day.

[knackeredMk1]

Modern 4 stroke bikes are not like the old CCMs. The old bikes had lots of grunt but ran out of steam quite early. In those days 2 strokes were comparably much revvier. With the advent of power valves 2 strokes developed much more low and mid range and this changed the whole nature of 2 stroke power. In the meantime 4 strokes were developed and got more peak power but this is done at much higher revs.

So the 4 strokes lost some of their low/mid range but developed more peak power whilst the 2 strokes produce much the same peak power as they have done for more than a decade but have much more low/mid range.

4 stroke - Noisy, high revving and lots of maintenance but lower emissions.
2 stroke - Better power through the range, lower maintenance, cheaper to make and lighter but little development so currently higher emissions.

So in MX a 125 2 stroke produces about the same peak power as a 250 4 stroke at about the same revs, but the 250 has more low/mid range. A 2 stroke 250 MXer will blast a 4 stroke 250 into the weeds.................

[longmoreuk]

So in MX a 125 2 stroke produces about the same peak power as a 250 4 stroke at about the same revs, but the 250 has more low/mid range. A 2 stroke 250 MXer will blast a 4 stroke 250 into the weeds.................

And therein is my point - shouldn't my crm - although not as frantic as a 250 MXer, at least be at around the same level as a 250 4 stroker.

I am not convinced mine is and that's why I was so surprised at the power of the WR.

[knackeredMk1]

First thing is to try them side by side and on roughly the same gearing. You will be surprised how much 'on v off' road makes a difference as does the gearing.

[longmoreuk]

A good point - would love to but I cant try them side by side, the WR is all but just a memory now!

In terms of the gearing on my bike, do I just count the cogs on each sprocket and report back!

[knackeredMk1]

Gearing - yes.

[fallenmikethebike]

I think I run about the tallest gearing, 14 /45 and whilst front end lift can be induced, some assistance is needed, if that's what you want, but I don't. The extra long pull on that gearing is awesome, and there's less of the " Bronco Billy" effect when idling along the road.I would say the CRM would only just lose out to my TTR 600 in straight out drag.I have no go faster bits on my engine, apart from the DEP pipe.
Start with the plug, does the colour look right?
Has the exhaust been decoked?
Reeds sealing good?
Power valve all doing it's bit?
What compression figures are you getting?
Mike

[fishtail]

i got a 48 on my rear and 15 on my front ( i think? its standard front sprox )

front end lift happens quite frequently if care isnt taken

no need to slip cluth or drop clutch - just WOT in 1st and it will come up when the valve opens...


( I love my ugly duckling bike ! )

[longmoreuk]

I will check the gearing first.

New plug already in.
Tried to decoke the expansion chamber but haven't done the silencer - Had put a wanted up on here for an exhaust in case its that. To be honest I think the exhaust is probably ok.
Reeds are beyond my knowledge at the moment.
Powervalve - have taken the cover off and it moves when I rev it, so assume that's fine.
Havent got the necessary tools to test the compression. I do however get the odd knocking noise now and again, mainly low revs but it doesn't happen all the while - I have just assumed its a bit of piston slap and nothing to worry about.

I have another bike, a CBR400 - that's quicker than the crm for sure. That's all I have to go off.

[fallenmikethebike]

Just take the plug out and hold your thumb over the plug hole, [ with the engine cold, and the ignition OFF, fuel ON.]. Give a good kick, there should be enough compression to just about lift your thumb if you apply a modicum of pressure.
You could then try dropping about a teaspoon full of your favourite 2T oil in the plug hole and repeating the sequence, if there's a significant uplift in pressure, voilà.
Not very scientific but it should give an indication.
Mike