CPI Oliver 125 Mods

281 posts in this topic

Posted

So I've been holding up on this for long enough, I've gotten in touch with Dan to do some upgrades to the scoot I have. I got a 58.5mm big bore kit with cylinder head, A8 camshaft (I would like to take some proper measurements of this cam for lift, duration overlap, etc, I find the online specs unacceptable, at Least Dan has some guidelines, the dyno graph is nice but that all comes down to what the engine build is), unrestricted cdi, hot coil, Nibbi CVT kit including racing variator, 13gram rollers, 115mm overdrive face, racing clutch with 1500rpm springs installed, an extra set of 1500rpm springs, 1500 rpm contra spring and the sickest clutch bell I've seen on the market (Only thing that was missing from this kit was the clutch sheave like NCY some call it the torque driver),, Nibbi carb kit including manifold, throttle cable, twist throtte, air filter, charge pipe and PWK 26mm slide carb (This is one seriously complete kit).I also got some extra jets for testing. I also got a heavy duty starter, heavy duty 20 sprag high torque clutch (I have a serious rattle when riding at lower speeds, its friggin noisy at idle and thats after I changed over to the Nibbi CVT so I know its not the rollers gone bad), oil pump (as I'm changing the starter clutch).

I wanted to do this as step by step as I could so I could feel the performance of each part individually. Of course the easiest one to do first was the CVT kit, or so I thought. I messed up the cheap china nut on the clutch and had to butcher it off by drilling and breaking the nut in half. Anyway, I the bike did a max of 80km/hr before any mods at all. I would like to point out one thing though I hear many of you saying that the speedos are wrong, but mine is right on point. I know the CPI company is out of Taiwan so I assume some of the components are of better quality that the chinese. I have tested the speedo against the GPS app on my Iphone and it is within +/- 3km/hr. I ended up replacing the variator and clutch nuts with grade 8 hardware, with some copper slip on the threads (thanks to piston for recommending). It got late into the night and I wasnt in the mood to put the cover back on (the clutch and bell look Awesome) so I took it to work the next day to see how it ran (Yes I know, its dangerous, I've since reinstalled the cover, the same day actually, my apologies to the HSE).

The increase in everything (acceleration, top speed, [COOL FACTOR]) was really noticible. I got a bit of clear road and when I looked down I say the needle at 100km/hr. My mind went back to one of the threads on the forum about the crap speedos, so I have to test this. I used the same app as Piston does when you all did the top speed runs. Low and behold it clocked in just over 100km/hr and SMILES EVERYWHERE. 20km/hr increase with just one mod, worth every cent.

Due to the way things are setup on the CPI Oliver, once I installed the variator and oversized drive face, the kick start shaft and spring cannot fit. this led me to do another check, do I really need the oversized drive face???? So I took some video with how much the belt was really rising on the variator and it didnt really seem like much to me. So I tossed back on the old drive face and whirled it up, at first glance it looked like it was going to fly off the face, so I put a mark on it with a marker. It rode as high as I think any belt should run without running the risk of falling off or getting damaged. Of course I didnt take into consideration that the variator was also oversized so it didnt matter if I changed the face. 

So I had to figure out if I wanted the reliability of being able to kick start the scoot if the battery died or if it gave any trouble starting (which it did). The starter solenoid that came with the scoot was changed 3 times since I got the scoot. Now I have gotten to the point where all of a sudden it wont start on a morning. I'll kick start, run it and once its all warmed up, if I switch off and try the electric start, no problem. Once its cold, big problems. Ended up getting a universal 12v starter solenoid for a car (guy said it was from England). 

Screw reliability of having the kick starter, I want to enjoy myself, kick starter shaft removed!!! Time for some pics and vids, I may have to come back in and add some words between, not sure how you guys do it.

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Posted

Clutch nut madness

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Posted

The first app didn't seem right to me so I used one that some of you used in the top speed run thread

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Posted

Great work!:clap:

You've got some skills for sure

Keep the updates and great pictures coming

Oh btw, sometime when I get back to a source I plan on digitizing the Stock cam and several various hot rod cams.

Not going to happen any time soon.

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Posted

Here are the pics of the clearance issue with the kick starter shaft. One day I'll take some time and reengineer it so I can get back a level of reliability. I should be able to kick start the engine even if the compression is a little higher than stock. 

I am having second thoughts about raising compression though, but that reason will be explained later on. 

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Posted

First, let me say good job! :ok:

Second, I love awesome threads like this! excellent thread.....

I have never installed one of these on a short case engine....In fact, most of the people that have purchased them for short cases, installed them on buggy's...I don't know if the buggy motors have a kick start.... :thinking: 

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This has me thinking about a bunch of stuff right now.... The NIBBI variator is 115mm, hence the over drive.... However, I have worked on a great deal of long case 150cc's, some have 115mm, some 112mm.......... I wonder if all short case engines have a 112mm... The only example of a 150cc short case I have is a ZNEN motor, it's stamped BN157QMJ... It has subtle differences from typical GY6 dimensions.... I think it has a stock 115mm....

The reason this all matters is because if is the ZNEN short case engine has a stock 115mm variator, that means it might explain why they have different kick start mechanisms.... I have them both in stock, but I never took the time to see the difference....  In short, it may be the case that you can buy a new kick start mechanism and CVT and it will work with the NIBBI CVT..... 

I am going to look into this over the weekend. 

Can you get a measurement of the diameter the of stock variator?

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Posted

Hey Dan,

I got some measurements for ya, actually 2, cause technically in not sure which one is the correct one. The first measurement is of the face itself (not the edge of the cooling fins) that is 107mm. If I measure to the tips of the fins, which in theory the belt can ride, disregarding the fact that it could tear up the belt, I got 115mm. I did my best to get some pics, my dad has my vernier caliper so I had to use a measuring tape. The last pic was of the marker line I used to check the belt level using the stock face and using the Nibbi variator with 13gram rollers. 

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Posted

Ok so to add to the build, I don't have much time on my hands to work on the mods so bare with me guys. When I took a look at the cylinder head, the intake and exhaust ports had some casting flaws as expected. The combustion chamber though I did not like one bit. The machining left sharp edges that will promote high heat zones in the chamber and we all know that doesn't help one bit.  Also I personally didn't like the transition the charge had to take once the intake valve is opened, walls on all sides.  I am in no way an expert or claim to be one but I have a fair understanding of fluid dynamics. Piston I hope you can input on this. My thought on transitioning those walls a bit to promote efficient cylinder filling instead of an initial turbulent flow. 

Long and short of it, I broke the edges with fine sand paper and ease the transition around the intake and between the valves where there is that ledge. I do not have access to professional tools and I know how much you guys hate dremels but that's all I got. So I did my best not to abuse it. Only to smoothen that rough casting and clean up the bowls a bit. I need to get some more bits to finish the bowls properly, I am not trying to remove material but just improve the flow. 

Valves look ok, I'll try to check the seat with dye if I get a chance. If not just the slightest lap only to see a surface then a hard run in should seat them properly. Will let you all know more about the head when I get a chance. 

The pics are before any porting. Will upload the worked pics in a bit. 

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Posted (edited)

I bumped my Cylinder head thread for ya, 

I could spend the rest of my life on Air Flow Dynamics and still not get half of it,

Oh btw that valve to seat will "Hammer in" within a few seconds of start up, please stay as far away from lapping as you can. if your close leave it alone.

Edited by pistonguy

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Posted

This is as much as I'll do to this head, hope you all dig it. My tools are very limited. As for the chamber I had a problem with the raised machined edge between the valves. I think it's bad for flow when the cylinder is filling, so I broke the edge back a bit and blended it best I could. I am not concerned with losing cc's here it's just a blend. Let me know what you think. Ohh yea I still have to come back and gasket match. 

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Posted

I think ya did just fine..:cheers: cheers

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Posted

Not too shabby,,, I'd run it

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Posted

Good Job! :ok: 

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Posted

Ok guys this is just a thought here, my good friend and neighbour has a suzuki 660turbo engine he bought for his old jimny, he sold it last 2 years but still has the engine. He is happy to give the turbo to me, please let me know your thoughts on the matter. If I do the setup, it will be draw through and I can get the piston, combustion chamber and valves coated. I'll be doing all the fabrication and building myself, so this may not happen very quickly at all. I'll also have to find my way into one of the oil passages for a feed, drain is easy. Carb will be the bad @$$ Nibbi PWK26 that Dan sent over. Please share your comments and concerns about this idea. This is supposed to be one of the smallest turbos out there. I'm not after big boost at all, only 4-5psi. All this will be done using the 58.5 BBK, I'll also have to test to see which cam is best. 

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Posted

I'd say it's too big,,,won't be enough exhaust to spin it up

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Posted

Yea, that was my biggest concern, I'll see if I can find some compressor maps online and also see if I can calculate the exhaust flow output from the gy6. In the end I may do it just as a test and prove it doesn't work. We all can get a kick out of it.

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Posted

Well in my opinion if it's made for a 600 your coming in at 25% I'd say it's a no go,,,

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Posted

Ahhh, very valid point, hmmm, any other idea if there might be a turbo suitable for this application? 

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Posted

Not that I know of but there is one guy that's developing a belt driven supercharger for thegy6 engine,,, that would be more in line with this engine anyways considering the relatively low redline and general poor quality of the metals in this engine ,,,

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Posted

Need some help here guys, decided to change the cam tonight took off the valve cover and set it to TDC and look at the cam. The engine runs great I've never had any problems. This is how I got the scoot. This looks wrong and feels wrong give me some feed back before I go messing with the new cam. Thanks in advance. 

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These are the markings on the flywheel. If it were up to me I'd say the cam was installed one tooth off

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Now it's lined up properly 

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Posted

Basically this timing is off. Smh I'll adjust the stock cam first and see how she works. Will let you all know the results. 

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Posted

Update guys, I fixed the cam timing and now she idles great. Consistent power throughout the rpm, it's a lot linear now. Before I found at lower rpm it would argue with me and upset the cvt. I blamed it on the bike being old but seems as though the timing was just screwed. Cheers to all of you who post, discuss and explain the ins and outs of these bikes and engines. Maybe tomorrow I'll throw in the cam I got from Dan. Big thanks to Dan for his awesome videos. 

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Posted

So wad it one tooth retard or advanced?

Glad you worked it out, great job:ok:

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Posted

The cam was one tooth retard, the upper chain guide is worn to hell and sitting cockeyed. My theory is that somehow not sure how the hell this may have happened that the chain jumped a tooth, doesn't make much sense to me. Yea the crank will want to rotate faster than the cam but that means there is some big problems with the tension area. Or maybe which is totally possible, whoever went into the engine last just messed up the cam timing. Big difference in the starting now, dammnnnn its a war to start the damn thing. It showed the typical symptoms of a retarded cam, crap low end and only gets good up at the top. Honestly I'd have to disregard the thought of the chain jumping a tooth, the engine doesn't seem to run as high an rpm now. :( I lost about 4km/hr at the top but gained a wider powerband. Let me know if what I'm saying makes sense, if not educate me please.

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