hazza
Scoot Member
Posts: 27
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Post by hazza on May 21, 2011 2:11:32 GMT -5
I am going to be fitting my 70 kit this weekend and was wondering about dissableing the oil pump in favour of premix.
What I'd like to know is, can I just disconnect it in case I want to reinstall it later or do I need to remove it all together.
If I can just dissable it what do I need to do?
Thanks
Harry
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Post by 90GTVert on May 21, 2011 3:43:47 GMT -5
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hazza
Scoot Member
Posts: 27
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Post by hazza on May 21, 2011 10:46:09 GMT -5
Thanks Brent,
OK I fitted the new barrel today and all went well, engine turned over without the spark plug, then when I put the plug in it seized up. Took the plug out and the piston had flattened the end, and I mean flattened. The piston is obviously travelling too far up the barrel.
I checked the old barrel size and it is 64mm the same as the new one. Only thing I can think of is that the head is more shallow and so the plug is sitting deeper into the barrel causing the problem. I am going to try the old head on and see if it still hits the plug. will let you know how I get on, but have had enough for today. Could I get a shorter plug or are they all the same length?
Any other suggestions.
Cheers
Harry
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hazza
Scoot Member
Posts: 27
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Post by hazza on May 21, 2011 11:33:52 GMT -5
Right I just went out and bought a new plug. The old one was a BR7ES and I noe have a B7HS which is 1/4 inch shorter. Popped it in and she is alive. Hope I haven't done any lasting damage to the piston. Just need to tune it for the 70 now, I upjetted from a 58 to a 65 which may be a little rich but I need to do a bit of testing. Tomorrow.  Harry |
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Post by 90GTVert on May 21, 2011 13:47:51 GMT -5
65 still sounds small to me. Also pay close attention for any strange noises that may be spark knock (detonation) since you haven't checked squish clearance.
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Post by lshigham on May 21, 2011 14:46:38 GMT -5
Your CPI's a Minarelli, isn't it Harry?
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hazza
Scoot Member
Posts: 27
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Post by hazza on May 21, 2011 23:54:50 GMT -5
I will listen out for that Brent. I wouldn't know how to measure squish clearance though anyway. The jet that was in was a 58 and ran a bit rich on the 50 so I took it up 10% ish so will check the plug when I start doing the running tests. Ishigham, yes the CPI uses a minarelli engine, so should be easy enough to tune, although I don't know what I'm doing most of the time. Harry |
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Post by lshigham on May 22, 2011 3:49:27 GMT -5
There's some useful stuff in here about mina jetting: blog.pedparts.co.uk/2011/05/moped-tuning-with-dyno.html''Here are some jetting increases for Yamaha Aerox *only*. Standard Aerox, standard airbox, standard exhaust :- 62 jet Sports exhaust :- increase from 62 to 68 (summer) or 70 (winter) 70cc Sports big bore kit :- no real change in jetting, perhaps increase of 2 Open air filter e.g. Polini Open Air Filter :- increase by another 28 this can depend on the filter fitted, if fitting a covered open air filter such as Malossi Covered then increase by 18 instead of 28...'' Although your isn't an aerox, it uses the same engine design. Don't take the jet sizes as gospel, as your Mina was made in china :lol: |
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hazza
Scoot Member
Posts: 27
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Post by hazza on May 22, 2011 4:13:29 GMT -5
Thanks for the link and info Ishigham.
Before putting on the exhaust it was fitted with a 47.5 jet and I upped it to 58. I did try a 65 but it was way too rich and fouled the plug so I put in a 62 which was still too rich so went back to the 58. I have now put in a 65 but not done any testing yet (weather is not good today). I may need to drop a bit but I don't want it running lean. I have also taken the little snoot thing off the airbox but may need to put that back.
Thanks again
Harry
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Post by 90GTVert on May 22, 2011 5:59:24 GMT -5
OK good, you are actually testing and selecting the right jet. Some folks just throw one in there and call it done if it runs at all, that's why I commented.
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hazza
Scoot Member
Posts: 27
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Post by hazza on May 22, 2011 11:10:57 GMT -5
Right, been doing a bit of testing and with the 65 it boggrd quite badly, changed the needle position to top but still bogging. Changed the jet to a 62 and set needle to lower position, now getting somewhere. A bit of hesitation on takeoff but then pulls OK. I swapped the rollers from 3.5 to 4.5 and it revs lower, but I can't get the damn nut off the clutch to change the springs, man this thing is tight. I may need to take it into work where we have a workshop and get the technician to remove it for me.
Checked the plug after a short run and it looks pretty good. Maybe a little dark/rich, but I'll leave it at that untill its done a bit of running in. Had to adjust the AF screw. It was only screwed out half a turn before but now runs better with one and a half turns out.
A bit more tweeking to do and I think we will be about there.
Harry
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hazza
Scoot Member
Posts: 27
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Post by hazza on May 23, 2011 12:09:55 GMT -5
Had another run out on the scoot today and the revs are really low untill it is doing about 20mph. It also loses a lot of revs when I hit a hill. Plug looks pretty good so I recon I will definately need to change the clutch springs and contra spring to allow it to rev better before take off and also maintain a little better speed when hill climbing.
The 50 barrel would hold 30 up hill (speedo speed) the 70 drops off to 25and looses revs.
I will be taking the clutch in to work tomorrow for the guys to sort the nut out and replace the springs. I'm hoping that this will do the trick.
Do you think I will need to do anything else?
Cheers
Harry
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hazza
Scoot Member
Posts: 27
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Post by hazza on May 25, 2011 10:00:36 GMT -5
Changed my clutch springs and contra spring today. The clutch springs are much stronger and the cantra is about half as long again as the original, and blue. It says 15% stiffer but that means nothing to me.
Not got them on the bike yet as I am still at work but I will be doing that in the morning and testing it out.
I hope it's not going to rev too high before engaging the clutch. The new springs are yellow but I've no idea what strength they are, I guess I will soon find out though eh.
Harry
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Post by scottkooi on May 25, 2011 10:06:30 GMT -5
Looking forward to hearing how your scoot runs with the new contra spring(1000-blue) and clutch springs(2000-yellow). I have ordered the same for mine and will be installing them next week. Interested in what gains and losses you experience.
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Post by 2strokd on May 25, 2011 15:14:15 GMT -5
You shouldnt need a new contra or torque spring unless your belt is slipping or the OEM one is worn out. Or you dont have light enough weights to use the stocker, in that case you will loose top-end speed.
Usually the yellow springs represent a 1,500 RPM increase in clutch engagement over what the stock springs rev to before the clutch engages. Red usually represents a 2,000rpm increase.
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