CPI SM250 & related banter

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Postby jaame » 15 May 2012, 08:30

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.
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before this dies out

Postby pommes king » 18 Jun 2012, 14:05

jaame wrote:Unless you make some rearsets yourself and turn it into a supermono.


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;
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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...
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Mag wheels?

Postby pommes king » 01 Jul 2012, 19:33

Anyone knows an affordable supplier in Taiwan? I'm afraid my rim is goner...
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Re: CPI SM250 & related banter

Postby TaFCoML » 20 Jul 2012, 16:22

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

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Derp.
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Re: CPI SM250 & related banter

Postby Ducked » 21 Jul 2012, 20:48

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

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.
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This post was recommended by TaFCoML (22 Jul 2012, 23:22)
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Re: CPI SM250 & related banter

Postby johancprinsloo » 23 Jul 2012, 11:56

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

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Re: CPI SM250 & related banter

Postby maunaloa » 24 Jul 2012, 02:57

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. :lol:

How long does it take you to change wheelsets from SX to SM?
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Re: CPI SM250 & related banter

Postby TaFCoML » 05 Aug 2012, 17:49

Update:

Here is the description from the mechanic as to what's going on in those pictures above:
引擎故障原因:

內鏈跳齒,導致引擎打壞、曲軸有異音。

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.
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Re: CPI SM250 & related banter

Postby rk1951 » 06 Aug 2012, 12:30

TaFCoML wrote:Update:

Here is the description from the mechanic as to what's going on in those pictures above:
引擎故障原因:

內鏈跳齒,導致引擎打壞、曲軸有異音。

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.



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.
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Re: CPI SM250 & related banter

Postby Ducked » 06 Aug 2012, 15:12

rk1951 wrote:
TaFCoML wrote:Update:

Here is the description from the mechanic as to what's going on in those pictures above:
引擎故障原因:

內鏈跳齒,導致引擎打壞、曲軸有異音。

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.



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.


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.
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(Incidentally, if the search button is your friend, you must have some bloody useless, dysfunctional friends)
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