CPI SM250 & related banter

Life Cars & Motorcycles
861

So they heard my bike and said some bearings were gone hey?

Thinking back, I took it down to the shop in Taoyuan about a year ago because the camchain was rattling like hell at 3000 revs. I left it there and asked them to fix it, and they changed a little external part, but basically didn’t do anything. If they are talking about the whining sound my bike makes at low revs, its done that from new. I suppose it could be a chattering bearing.

Pommes when you go down there to get the rebore done, could you ask them what a service costs and how much it’s likely to cost to change the camchain tensioner on my behalf? I doubt I’ll make time to go back there any time soon. I’m not going to ride my CPI again for a few weeks until after that MTB race in June. I want to get some practice in on that bike.

Looking at resale values on ruten, I’d say that changing the suspension would not be a total waste. Most of the bikes for sale with the upgraded suspension have a lot of other mods done too, but I think with standard suspension you’re talking about $60-70k, with USD forks you’re talking about $85-90k. I’m on the fence.

w.r.t. lowering the front end. In my opinion the head angle is too steep anyway and dropping the forks would make it steeper. I think if you want the bars lower you’d be better off keeping the original fork length and fitting flat or lower bars. Unless you drop the back as well, but then you’re going to deck it out even easier than you already are doing. Unless you make some rearsets yourself and turn it into a supermono.

862

ha - a 20hp-superbike - unless for riding on track only, no thanks. I actually might have the cylinder honed to 76mm one day - but not now. There’s a couple more things I can do first… untill then - I’m still loving it;




too bad that there are so little people out there using it - it would be a perfect racing cup bike. Or even offer a supermono-kit for it…

863

Anyone knows an affordable supplier in Taiwan? I’m afraid my rim is goner…
http://www.flickr.com/photos/pommesking/7478199426/in/photostream

864

Please forgive the knuckle-dragging, but could anyone help explain what is wrong with this engine?






865

Seems to have come apart. You’ll need to put all those bits back together before it’ll work. :slight_smile:

No expert, but the cam lobes / journals look a bit scored, though not horribly so.

Where was your finger (immediately) before it acquired that metallic paint job? I’m guessing you were poking the cam bearing surfaces, but you could have been poking around in the gearbox.

Some fine metallic sludge is, I think, normal. There was always some in my RZR box when I opened it up, but it was pretty old.

I’d say that, as a rule of thumb (finger) there shouldn’t be many particles big enough to feel with your fingertips. Lots of fragments suggest something (like a bearing cage) is breaking up.

Cam, ring, gear teeth, roller/needle and ball-race bearings produce ferrous wear particles which tend to look black, and are magnetic.

Bore and piston wear produces aluminium wear particles which (in oil) tend to look grey.

Shell bearing wear can be grey or copper/bronze in colour. Some gearbox components (eg synchro dogs) can also produce copper wear particles.

The sludge on your finger looks grey-black. I can’t see any fragments. Might be worth putting a magnet on it. If its mostly non-ferrous with no fragments I’d guess its normal wear.

Do the cam bearings have bearing shell inserts (good)[Edit: Looks like shell bearings in the top pic. Endedit], or does the cam just run directly in the head, as I believe is the case with some motorcycles (bad)?

What oil do you use? Has it got enough zinc in it? Most current motor oils don’t have.

866

Hi I recently bought a CPI SM250.

It have two sets of wheels and tires.

For road and off road.

I see a lot of mentions about guys riding out to Zhubei, this is where I m located. I also see posts about going to the CPI shop in Zhubei, is it the shop in Hsinchu downtown or Zhubei. As far as I know the CPI dealer is in downtown Hsinchu.

If anybody is interested in going to take a ride, please give us a shout. I have two Taiwanese mates who also has motards. But they are not always keen or available.

There is a big dirt bike meet and races this Sunday here in Zhubei. Feel free to drop us a line if you want to come take a look.

Thanks a lot
Johan

johancprinsloo@gmail.com

867

Johan, welcome to flob and the gearheads in the C&M forum.

Yes, the CPI dealer in NewZoo offers free transportation from the TRA station to his shop. Walk down the street. :laughing:

How long does it take you to change wheelsets from SX to SM?

868

Update:

Here is the description from the mechanic as to what’s going on in those pictures above:

[quote]引擎故障原因:

內鏈跳齒，導致引擎打壞、曲軸有異音。[/quote]
Anyone out there able to help with a better translation than Google’s?

I’ve sent CPI an email and am waiting to see whether they’ll offer any assistance.

869

[quote=“TaFCoML”]Update:

Here is the description from the mechanic as to what’s going on in those pictures above:

[quote]引擎故障原因:

內鏈跳齒，導致引擎打壞、曲軸有異音。[/quote]
Anyone out there able to help with a better translation than Google’s?

I’ve sent CPI an email and am waiting to see whether they’ll offer any assistance.[/quote]

It looks like either the camshaft or crankshaft gear broke a tooth which ultimately made your engine malfunction. From that description, it doesn’t say which gear caused the problem.

870

[quote=“rk1951”][quote=“TaFCoML”]Update:

Here is the description from the mechanic as to what’s going on in those pictures above:

[quote]引擎故障原因:

內鏈跳齒，導致引擎打壞、曲軸有異音。[/quote]
Anyone out there able to help with a better translation than Google’s?

I’ve sent CPI an email and am waiting to see whether they’ll offer any assistance.[/quote]

It looks like either the camshaft or crankshaft gear broke a tooth which ultimately made your engine malfunction. From that description, it doesn’t say which gear caused the problem.[/quote]

Call me racist, (and ignorant, since I don’t know any Chinese) but my impression is that, even allowing for any translation problems, Chinese is a language ill-suited to technical (or any other kind of) precision.

I’d interpret “Camshaft gear” to mean camshaft sprocket. If it broke a tooth you’d probably be able to see it on an OHC engine. If it stopped the engine there’d probably be valve damage, which isn’t evident in the above pictures.

“Crankshaft gear” seems to me to imply a gearbox failure. These machines have a recorded history of gearbox problems, but AFAIK there’s been no description available of exactly what broke.

I can’t see why a gearbox failure would affect the engine, unless the drive to the oil pump was compromised.

871

[quote=“Ducked”][quote=“rk1951”][quote=“TaFCoML”]Update:

Here is the description from the mechanic as to what’s going on in those pictures above:

[quote]引擎故障原因:

內鏈跳齒，導致引擎打壞、曲軸有異音。[/quote]
Anyone out there able to help with a better translation than Google’s?

I’ve sent CPI an email and am waiting to see whether they’ll offer any assistance.[/quote]

It looks like either the camshaft or crankshaft gear broke a tooth which ultimately made your engine malfunction. From that description, it doesn’t say which gear caused the problem.[/quote]

Call me racist, (and ignorant, since I don’t know any Chinese) but my impression is that, even allowing for any translation problems, Chinese is a language ill-suited to technical (or any other kind of) precision.

I’d interpret “Camshaft gear” to mean camshaft sprocket. If it broke a tooth you’d probably be able to see it on an OHC engine. If it stopped the engine there’d probably be valve damage, which isn’t evident in the above pictures.

“Crankshaft gear” seems to me to imply a gearbox failure. These machines have a recorded history of gearbox problems, but AFAIK there’s been no description available of exactly what broke.

I can’t see why a gearbox failure would affect the engine, unless the drive to the oil pump was compromised.[/quote]

Yes that Chinese description was very vague for sure and needs to be more precise. Ducked the Chinese language is not ill suited to technical precision. Learn to speak it and then you will know what you are talking about.

872

Tough luck TaFCoML! Where are you going to get the engine fixed at? Did you buy a used CPI or new? What year is your bike?

873

[quote=“rk1951”]
Yes that Chinese description was very vague for sure and needs to be more precise. Ducked the Chinese language is not ill suited to technical precision. Learn to speak it and then you will know what you are talking about.[/quote]
Fair enough. But will anyone else?

I’m just going by the vague-tastic way they tend to write in English, which Chinese speakers have told me is at least partly a result of translation from the Chinese.

As you say, I know nada, and its off-topic anyway.

874

I bought it new in the second half of 2009. Unfortunately at the moment I’m stuck in the middle of some finger pointing between CPI and the bike shop where I get it serviced.

Btw, how does the bike shop’s quote of 30k sound for repairs?

875

[quote=“TaFCoML”]
Btw, how does the bike shop’s quote of 30k sound for repairs?[/quote]

I would check with Michael in Hsinchu; for ~amount, he offers a big bore kit + piston + carb. Add crankshaft(gear) and you might end up with some more HP as well.
Or find a different engine from an illegal bike and give it a go :smiley:

Even if you do the 30k repair, your bike might be worth only 60k. So you don’t have much to loose IMO…

876

Update #2:

I’ve gotten a second quote for the repairs: 25’000 NT. Much of a muchness really. An interesting tidbit that came from chatting with this other mechanic was that the SM 250s released in 2008 and 2009 have often suffered from a similar defect arising from some part of the engine (I’m afraid this part I couldn’t make out clearly - maybe the cams?) not being strong enough and failing.

Still in coms with CPI HQ and will update what their response is soon. Thanks for the help all

877

[quote=“TaFCoML”]Update #2:

SM 250s released in 2008 and 2009 have often suffered from a similar defect arising from some part of the engine (I’m afraid this part I couldn’t make out clearly - maybe the cams?) not being strong enough and failing.

[/quote]

You havn’t described your symptoms at all.

That’s likely to be quite a bit more informative (at least to me) than some mechanics musings in the original smoke-and-mirrors Mandarin.

Those camshafts might be a bit scored, but they don’t look anything like “failed”.

"Failed"would imply bad enough to stop the engine.

This in turn would either imply broken, which would imply consequent broken/bent valves and damaged piston, or “wiped”, i.e. worn almost flat, which they arent.

In the abscence of any definite info, my money would still be on a geartrain failure.

878

My vote is tranny failure. The nemesis of the early CPI SMs.

879

Fair enough. The most I can be sure of is that he said he believes my troubles have occurred in other 2008/9 models. He added that CPI strengthened the offending doohickey in later bikes.

My symptoms began with my bike becoming more difficult to start for a few days. Then later while driving the engine suddenly started making a horrible noise and could no longer go over 3000 rpm in any gear. I made it to a mechanic going around 20km/h.

880

Fair enough. The most I can be sure of is that he said he believes my troubles have occurred in other 2008/9 models. He added that CPI strengthened the offending doohickey in later bikes.

My symptoms began with my bike becoming more difficult to start for a few days. Then later while driving the engine suddenly started making a horrible noise and could no longer go over 3000 rpm in any gear. I made it to a mechanic going around 20km/h.[/quote]

Seems consistent with a bearing failure, but I suppose from that information alone it could also be a broken piston ring/partially seized cylinder. They’d probably have seen that though.

Since starting difficulty implies it happens in neutral, I think that tends to exclude the final drive shaft and selector dogs, but includes just about everything else, since (at least in cars, and AFAIK motorcycles are the same) all the gears go around all the time.

Did you notice if the noise stopped when you pulled in the clutch lever?

If it did, that would, (I THINK) tend to indicate the geartrain.

If it didn’t, it’d tend to indicate crankshaft bearings or big end, though they are probably less likely to make a screechy noise, since they’ll likely be plain shell bearings.

Or I’m talking bollocks again.

Sorry, not very helpful.