Little bit of advice for an unseasoned rider.

InkedMuttley · Renault 5 Driver Joined: 01 Dec 2015 Karma :

I'm a new member haven't posted in an introduction section but everything you might want to know is in my public bio.

I'm fairly new to biking I didn't take my CBT until last December and only had a bike (WK Wasp 125) for a couple of months before I realised that it had an appetite for eating cylinders and cylinder heads so I got rid. The bug bit again in October and I purchased another bike a CPI GTR, looks like a cross between a bike and a scooter, it was originally a 50cc but when I bought it it had a 70cc cylinder upgrade on it and no MOT. On the way to the MOT the first time it broke down 9 times in 8 miles before I finally thought sod it and took it home in a van.

Sorted it to the best of my ability and tried to take it for an MOT again and it broke down less than half a mile from home and couldn't get it going again. Took it to my good lady's home and left it in her garage and have stripped the engine, upon stripping it I discovered that the ring was very polished on the sides, there is a lot of the original honing still visible but there's also a little gouge in the cylinder wall. I thought it may work with a new ring so have done it but it still isn't getting any compression (about 5psi) so I've finally bit the bullet and have a new cylinder kit on the way which I'm hoping it works.

However I found when we stripped it down that for some reason someone had stuck a steel dowel in the oil feed pipe for the autolube system (it's a 2 smoke), so the person before me had been running it on Premix. I now have 2 or 3 questions that I need answering.

1: With a brand new cylinder is it likely to run knowing the damage from the last cylinder or am I going to need to rebuild the whole engine?

2: Is the fact that I'd been running it on straight petrol (didn't know autolube was disabled) to blame

3: I've decided to run premix myself as it says on aguide that the standard oil pump wouldn't be able to put out enough oil to compensate for the increased cylinder capacity but at what ratio would it need to be roughly, it's a 9 litre fuel tank.

Sorry for the long winded post but I dearly hope one of you wonderful people might be able to help me, and greetings from sunny (not) Lincolnshire!

Oh and this isn't my bike but mine is identical

https://scooterunderground.ca/products/gas/images/CPI_GTR_Blue_2008.jpg
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Ariel Badger · Super Spammer Joined: 02 Dec 2006 Karma :

If it has rum without oil you may have damaged the big end, little end and main bearings as well as the crank seal. did previous ouner not say it was on premix?
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InkedMuttley · Renault 5 Driver Joined: 01 Dec 2015 Karma :

No there was a bit of confusion about the bike to be honest it was bought from one bloke, the lad who bought it took a loan off his friend and gave him the bike as security and then told him to fuck off as he didn't want the bike anyway then muggins here bought the bike.

But nobody at any time told me it was premix they'd been running.
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Burnzy1989 · Nitrous Nuisance Joined: 06 Apr 2009 Karma :

I would run it at 32/1 so it's works out to 150mls of oil to 5 liters of petrol. But what you must check is the jetting is corects for running premix as it will cause it to run lean. you will find you could run the bike again but will end up with rumbling big ends and main bearings. I would rebuild it completely if the bearings have picked up on the races or siesed they are scrap .

InkedMuttley · Renault 5 Driver Joined: 01 Dec 2015 Karma :

Ariel Badger · Super Spammer Joined: 02 Dec 2006 Karma :

As you do not seem happy with the advice freely given here why not ask your bike mechanic?
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InkedMuttley · Renault 5 Driver Joined: 01 Dec 2015 Karma :

P.addy · *Formerly known as* P. Joined: 14 Feb 2008 Karma :

Do you not think it's a wiser idea to shift that on and grab a CG or YBR? They don't really break down. This is a now tuned 70cc ped which you seem to know a lot about given your sig. 18000rpm crank isn't needed so just get shot of it and buy a reliable 4 stroke.

WD Forte · World Chat Champion Joined: 17 Jun 2010 Karma :

FBSF · Nitrous Nuisance Joined: 23 Mar 2011 Karma :

Having had experiences of an RD125LC stroker that cost me an absolute fortune when I was a teenager, due to it being "tuned" and running lean, I'd cut your losses. I had to get shot of it once the engine had holed it's third piston, despite going up to a 25% bigger main jet.

It'd also be a damn site cheaper to insure a bog-standard 125 bike or scooter rather than your modded-to-the-moon 'ped...you have mentioned all of the mods to your insurance, haven't you...? Confused

You don't want to end up with an IN10 for no valid insurance - it'll cripple you for years.

A 4t scooter will happily do 60-65mph, will do a shed load more to the gallon and generally won't blow up anywhere near as often!

InkedMuttley · Renault 5 Driver Joined: 01 Dec 2015 Karma :

P.addy · *Formerly known as* P. Joined: 14 Feb 2008 Karma :

But does your logbook say 50cc or 70cc... The 2 are different.

You are able to sell that ped to fund a 125 you know. You need about 600 quid. That ped will sell for a few hundred to some pikey go fast init lad. Ebay it.

Tierbirdy · Crazy Courier Joined: 25 Jun 2014 Karma :

Youve bought a knackered lemon of bastardised parts, probably by some spotty 16yr old YOOF who wanted to show off his hardcore modding skillz and race his mates on a "BANGIN 70SEESEES OF POWAH MATEY, PIGS WONT EVA NO LIKE"

You say you cant afford a decent bike and stuck trying to fix this, but its going to be a total money pit trying to get it working.

Set fire to it, claim it on insurance, buy a cheap banger of a 4T 125 that'll still be more reliable. Razz

Ariel Badger · Super Spammer Joined: 02 Dec 2006 Karma :

You say it is insured and all mods declared, what insurance level do you have TP, TPF&T, Full Comp?
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Pete. · Super Spammer Joined: 22 Aug 2006 Karma :

Burnzy1989 · Nitrous Nuisance Joined: 06 Apr 2009 Karma :

Looks like you best off selling it as said above. I can asure you it will end up costing you more than it is worth, it request a full rebuild and while your stripping it down I bet you will end up finding more wrong with it that right. A cg 125 is not a bad potter about but is ok if your not a speed freak. Or save your money and do your full bike test as it seems people who are 16 17 seem to be unlucky as there are no more 125s left as the big four have stopped production of two strokes. A Kwak kmx 125 or a yam dt 125 a honda nsr 125 or a suzuki dr 125 4 popper . I do feel sorry your generation never had the luck of getting cheap good bikes.

InkedMuttley · Renault 5 Driver Joined: 01 Dec 2015 Karma :

Burnzy1989 · Nitrous Nuisance Joined: 06 Apr 2009 Karma :

Hahaha lol yha it is. I wouldn't mess about with it to be honest if I were you I would spend as little on it get it running and flog it as you will get more for it running. Then use the money to do you full test it cost roughly 500 to 600 pounds. It's worth doing best thing I did and is not as hard as you think pluss bigger bikes are alot more fun.

Ariel Badger · Super Spammer Joined: 02 Dec 2006 Karma :

InkedMuttley · Renault 5 Driver Joined: 01 Dec 2015 Karma :

Okay I'm officially lost. I've got the whole thing rebuilt it's got a brand new top end and has brand new gaskets all over it, there's also a brand new spark plug, brand new coolant, brand new oil...everything just about is brand new.

There's a good strong spark, the carb and cylinder is getting fuel and oil as it should...and it still won't start, it's clearly got compression because the fuel is being expelled from the spark plug hole when I checked for a spark but it still won't go. Admittedly I have managed to snap a bolt for the exhaust (enough left to get stillsons on it to wind it back out and replace it)

Would the exhaust not seating properly stop it from building up enough compression to start it or am I absolutely fucked and the thing is never gunna go again?
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Burnzy1989 · Nitrous Nuisance Joined: 06 Apr 2009 Karma :

It should start with out the exhaust but fundamentaly it needs to he gas tight being a 2 stroke as the exhaust plays a big game of making power.

What you must do next is check your reed block and make sure the reeds are not broken in any way .

Then do a compression test and see what sort of presume is there.

If all is ok then make sure your carb is clean and there is no dirt or water in the bowle.

And did you check the ring gaps when you rebuilt the top end and did you make sure you put the piston in the right way .

Or did you put loads of oil on everything thing when you built it up.

P.addy · *Formerly known as* P. Joined: 14 Feb 2008 Karma :

PLEASE STOP THROWING MONEY AT THIS.

YOU WILL HAVE FUNDS FOR A 4 STROKE 125 IN NO TIME.

PLEASE STOP THROWING MONEY AT THIS.

YOU WILL HAVE FUNDS FOR A 4 STROKE 125 IN NO TIME.

PLEASE STOP THROWING MONEY AT THIS.

YOU WILL HAVE FUNDS FOR A 4 STROKE 125 IN NO TIME.

PLEASE STOP THROWING MONEY AT THIS.

YOU WILL HAVE FUNDS FOR A 4 STROKE 125 IN NO TIME.

InkedMuttley · Renault 5 Driver Joined: 01 Dec 2015 Karma :

stirlinggaz · World Chat Champion Joined: 22 Jul 2007 Karma :

hi,
you should have smothered everything with 2t oil before re-assembly (piston etc) its common practice.
it burns off, once you get it running.

an air tight exhaust is critical in a 2t.

do a compression test, with a decent compression tester & post results (remember to hold throttle wide open to get an accurate psi) do it a couple of tines & get an average.
if you have decent compression :
mix up some petrol & 2t oil at the ratios mentioned earlier & make yourself a remote fuel tank. (empty fairy liquid bottle & length of fuel hose does the job)
connect it up to the carb.
also put some 2t oil in the oil tank.
stick a new spark plug in & test oil pump/bleed it whilst its running off the remote fuel tank/pre-mix.

btw reeds live in between carb & cylinder (google 2t motorcycle reed block/reeds for image)

cheers,
GAZ

Copycat73 · World Chat Champion Joined: 11 Jan 2013 Karma :

the only sensible suggestion i have is to double check the ignition timing.. Thumbs Up

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