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Post by tsimi on May 18, 2015 2:36:34 GMT -5
This thread is about installing my Polini 70cc Sport BBK into my 2003 CV50R Jog. I want to keep some sort of record that might help me in the future when adjusting stuff or getting advice/help. Here a list what I have done so far. - Prepared all necessary tools, ...i hope.
- Checked piston ring gap with feeler gauge.
- Put the piston rings on the piston.
- Chamfered the edges of the ports.
Today I got my ordered stuff that are needed for the BBK install.   Now all I need to do is to think of a good way to hold the scooter in place/up when removing the engine under it. Getting a bit nervous and anxious since I have never removed nor opened an engine before and since I am tight on a budget everything must work out the first time. (*fingers crossed) I will be posting more pics and info if time allows it so stay tuned... and wish me luck. Thanks! |
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Post by 90GTVert on May 18, 2015 6:04:06 GMT -5
If you have a garage to work or some very sturdy object overhead you can use ratchet straps to lift the rear off the ground just enough to get the engine out, but be sure to support the front somehow so it can't move or it will want to fall over. You can get some sort of crate or stool and lift it onto there and use ratchet straps to secure it so it won't fall off or over. Some just have a friend lift the scoot long enough to roll the engine out when ready and then set the rear of the scoot on something. Sometimes jack stands can be placed under the frame. One of mine has footpegs welded to the frame and they make an easy spot for jacks tands. Whatever method you choose, think it out first so you won't tip the scoot over or damage anything supporting it improperly. Take your time with the whole process and pay attention to the details and you will likely see that it's not as big of a deal as you probably think it is right now.
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Post by tsimi on May 18, 2015 6:47:09 GMT -5
90GTVertThanks for the advice Brent, appreciated! Unfortunately I don't really have a Garage more like a parking space with a roof over it. Not really sure the roof hold the weight though. I will have to go over it again and, as you said, make sure that the scooter is stable and won't dip. Tomorrow I should get the ratchet straps from a friend of mine and I will see with what I can come up. There is another issue that needs more clarification. In your tutorial you said that you need a torque wrench to close the 4 nuts on the cylinder head. And you mentioned something like final torque is around 15ft-lbs. Here we have only Nm on our torque wrenches so I used a converter and it says 15ft-lbs => 20.33726925Nm According to my local bike store guy a Jog stock cylinder should be closed with 10Nm and according to some service manual of a different Yamaha Jog in Europe (CS50) 14Nm should be used. The Polini manual doesn't say anything about it. So I am now a bit confused and stuck between 10Nm, 14Nm and 20Nm. How do other guys here in the forum close the cylinder nuts? All use Torque wrenches?
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Post by 90GTVert on May 18, 2015 6:56:56 GMT -5
I'd go with the 14Nm spec if not 20. 14nm is ~10.3ft-lbs and I've never torqued one to less than 10ft-lbs. I generally do 15ft-lbs on mine, but I would not exceed that and it's prob safer to stick with 10-12ft-lbs.
I know others here do it by hand. You can certainly do it by hand being mindful that you don't want to ruin threads in the cases by going after it too hard.
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Post by tsimi on May 18, 2015 7:17:03 GMT -5
Roger that! I can get the torque wrench and most of other special tools from the bike shop. So I am covered there. 14Nm it is then, unless birdman or nelson tell otherwise. Those two guys are Jog maniacs I hope they chime in and give the one or other advice. |
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Post by bryans on May 18, 2015 10:21:44 GMT -5
 I like this thread
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Post by thatcrazyguy on May 18, 2015 10:43:26 GMT -5
I'd go with the 14Nm spec if not 20. 14nm is ~10.3ft-lbs and I've never torqued one to less than 10ft-lbs. I generally do 15ft-lbs on mine, but I would not exceed that and it's prob safer to stick with 10-12ft-lbs. I know others here do it by hand. You can certainly do it by hand being mindful that you don't want to ruin threads in the cases by going after it too hard. I made the mistake of tightening it by hand and stripping the threads in the case. Luckily, I was able to fix it with heli coils, but id use a torque wrench from now on  |
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Post by nelson on May 18, 2015 11:32:07 GMT -5
I do torque by hand, but am pretty sure it's very close to 12ft #. I have torqued a lot of heads on 2 stroke vehicles. Make sure to alternate while tightening. Tighten one a few ft pounds then the one on the far corner. After you run it and get it hot it's a good idea to check all 4 nuts again. This is only the way I have always done it and been successful. MAKE sure your head studs are screwed in case all the way so you don't pull then out. Sometimes they back out when taking the head nuts off the original head.
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Post by nelson on May 18, 2015 11:34:32 GMT -5
Also, when I put a new cylinder on I get 2t oil on my finger and coat the inside of cylinder and a squirt on wrist pin bearing.
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Post by birdman on May 18, 2015 12:47:22 GMT -5
Lather everything well in 2t oil, dont put it together dry. One thing I do and it might be overkill, but once I got assembled, I start the engine with the fan shrouds off and let it run for 1 min 45sec to 2 minutes, shut it off and re-torque the head. Also like Nelson said, torque the bolts in an "X" pattern. You got this tsimi after you do this you will see how simple it really is. |
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Post by tsimi on May 18, 2015 17:54:59 GMT -5
nelson birdmanThanks for the hint with the studs. Good to know. I will follow Brents BBK install tutorial where he mentioned that the inner side of the cylinder, needle bearing and pin should be lubricated with 2T oil. So i got that covered. Did more research on the nut tightening issue and found 2 Japanese BBK install tutorials for Jogs. Both recommend to tighten the nuts with 14Nm. So I just go with 14Nm then as Brent recommended before. Another thing metioned in one of the tutorial was that the stock oil pump is not enough and therefore premixing is recommend. And instead of using regular gasoline you should use high octane. Is this true? And what about the Mainjet? what would be a good starting Jet? Stock is 68 so i was thinking to start with an 80-82?
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Post by nelson on May 18, 2015 22:11:27 GMT -5
I have always ditched the oil pumps on all my 2t be it atv it scoot. I just don't trust them with my investment. I mix at 32:1 with Lucas semi synthetic. As for jetting start big and go gown. Rich doesn't ruin engines but lean does. So start big, it will be boggy. Drop down a size. Keep doing this until it runs perfect and then go up one jet size. Put in a fresh plug and do a plug chop. I'm not sure what all you have done? If you are only running a Bbk then I would say start around 85. Keep in mind the oil pump doesn't draw through the main jet so you only have fuel going through the main when using the pump. I say this because if you premix some of the fuel drawn through the jet will not be fuel but oil also. Depending on compression ratio determines octane. If you have pre ignition due to high comp ratio you need a higher octane. The only thing high octane will hurt is you pocket. I have heard guys who run the oil pump and put a bit of oil in the gas also. Can't comment as I have never done it. Make sure you put the arrow on the piston facing the exhaust. Turn everything over slowly once assembled to make sure nothing is binding. Just slow push the kick starter or turn engine over by spinning the fan by hand(watch your fingers) make certain the circlips are in their seats, be very cautious with this.
I always put on clip in the piston before I start to install piston so I only have to do one when I get down there. Make sure rings are lined up with the pins on piston and don't force cylinder on. I think that's it!
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Post by Elektrey on May 18, 2015 22:17:15 GMT -5
Main jet: start on the high side and work your way down.
Premix: already there. Even if the oil injection WAS enough are you going to really bet all of your work you put into this kit on an oil pump to not fail on you?
High octane: I put my stage 6 sport pro kit on and it has a squish head for higher compression. Apparently it's not high enough to cause knock because i'm using 87 octane just fine no pings.
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Post by tsimi on May 19, 2015 0:34:15 GMT -5
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Post by 90GTVert on May 19, 2015 7:05:48 GMT -5
With sport kits you really shouldn't HAVE to pre-mix. Many don't. I'm just another that doesn't trust the oil injection as much as pre-mix.
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I like this thread
