|
|
Post by oldgeek on Nov 11, 2018 21:51:50 GMT -5
I started today with adding some octane boost to the tank, I just bumped it up to 97. I made a short run or two and made some tuning changes. The knock (if that is the sound I am hearing) sounded better, but you can hear it in the video easily. I found out it sounds worse in the video than what I could hear while I was riding. Near the end of the run when I was at max speed you can hear it cut out, sorta sounded like the bowl emptied out. I made a bunch more changes and short runs without the longer WOT and I felt like it was slightly better. I also lightened the weights in the variator from 54.67g to 49.57g The junk guides on my brand new variator shattered after only 4 miles, luckily I had some better ones on hand to replace them. I ended up doing another WOT run video that was basically just like the first one. The scooter sounded like it ran the bowl dry or something. At that point I finally decided to do a compression test, and took a look at the plug. Wonder how accurate the accutron is    No wonder it is knocking LOL! I guess I gotta do something about compression. |
|
|
|
Post by ryan_ott on Nov 11, 2018 22:15:11 GMT -5
I think it sounds pretty good. Didn’t sound like knock just exhaust rattling unless that’s what your taking about. Speed looks good. Get that compression adjusted and you should be all set.
|
|
|
|
Post by oldgeek on Nov 11, 2018 22:38:05 GMT -5
I think it sounds pretty good. Didn’t sound like knock just exhaust rattling unless that’s what your taking about. Speed looks good. Get that compression adjusted and you should be all set. Damit! I bet that is pipe rattle. But what do you think is making it cut out after a short WOT run? I wonder if the vacuum petcock flows good enough to keep up? |
|
|
|
Post by gsx600racer on Nov 11, 2018 23:04:10 GMT -5
Sounds good. Not sure what that noise/rattle is just off idle tho. If I had to guess with that big ol piston and crank spinning/flying around there are more vibes than normal and something is rattling.
Id start lifting(shimming)the head to get your compression down.
They make clear bowls for your carb, might be worth having to see if your starving for fuel.
|
|
|
|
Post by oldgeek on Nov 11, 2018 23:24:20 GMT -5
...... Id start lifting(shimming)the head to get your compression down. They make clear bowls for your carb, might be worth having to see if your starving for fuel. The squish is pretty tight, I hate to open it up any. I may just break down and do the calculations. Or I could just enlarge the combustion chamber a bit. |
|
|
|
Post by gsx600racer on Nov 11, 2018 23:56:03 GMT -5
...... Id start lifting(shimming)the head to get your compression down. They make clear bowls for your carb, might be worth having to see if your starving for fuel. The squish is pretty tight, I hate to open it up any. I may just break down and do the calculations. Or I could just enlarge the combustion chamber a bit. I hear what your saying. The only option would be to re-machine the dome in the head. Make it deeper. But for shits and giggles id try a shim first and see what you get. |
|
|
|
Post by 190mech on Nov 12, 2018 5:22:56 GMT -5
Squish band width should be 50%(12.5 mm each side),I'd pull the head and do the math,see if the piston has touched the squish band,if so adjust it up,if not leave it tight..If you can slow down your rotary table to a crawl,make up a head hold fixture kinda like this and clamp it upside down to make smooth cuts while spinning;  Here is an ideal combustion chamber layout from the RSA125,note the sharp edge at the bowl to squish,keeps the flame front from traveling to the edge of the piston..  PS,IT SOUNDS GOOD!!!! |
|
|
|
Post by 90GTVert on Nov 12, 2018 7:43:18 GMT -5
I also think you're hearing the pipe rattle. If you really want to listen for spark knock, roll on and off of the throttle and it usually gets bad at some point in that process if it's an issue. Even then, sometimes it can be a little lean or maybe just taking out a degree or two of timing to cure it if you're lucky. When it does it at steady WOT and jetting or reasonable timing changes don't cure it, then you would probably need to lower compression. Head gasket thickness may be the easy way to go about figuring that one out. Not ideal, but if you add X amount of volume with whatever gasket change and everything is peachy then you would know that that amount of volume (or maybe less) added to the combustion chamber should get you where you need to be and allow the tighter squish that you'd prefer. Down side there is that if you ever build another similar setup, you wouldn't know what number to shoot for for sure with CCR... but if you don't like measurements and math it doesn't matter and at least you can have some data from the compression test before and after changes to help there.
If you add a larger main jet and that coincides with cutting out after a period of WOT, or decreases the time that you can stay in the throttle, then it's likely either the float height or other fuel delivery issue. I was having that problem with T2 and it surprised me how much it changed the duration before cutting out by changing main jet sizes.
|
|
|
|
Post by oldgeek on Nov 12, 2018 23:16:12 GMT -5
I want to get rid of the rattles, so first I worked on the pipe today. We brazed the mount for the silencers clamp back into position and attached the clamp. Followed that with some brief tuning runs, and the silencer clamp def helped with one of the rattles. There was still a vibration or something and definitely some spark knock here and there. This evening I continued working on the pipe some more. I extended the pipe mounting bracket so it would reach the relocated rear pipe mount, and in the process beefed the bracket up a bit. It is pretty solid now. I did some more tuning runs and checked for rattles. There is still something causing a resonant vibration somewhere, and of course the occasional spark knock.  Stupidly I have been dogging this thing trying to tweak the carb just right, but it is so much fun having to slide my hefty mass forward to keep the front end down.  After doing a bunch of launches and a burnout I could tell something was up with the CVT again. I pulled the CVT cover off and there were ramp plate guide pieces everywhere again. I got 4 miles out of the krap pair that came with the variator, and around 10 miles out of the Dr pulley guides I put in yesterday. I did not mention it, but the first time I replaced the guides I had a little problem getting the ramp plate to slide off of the crank. And it appeared the splineless ramp plate had slipped on the crank just a little. So when I tightened the variator up I used the impact gun without the torque stick to get the thing tighter. This time it was even tougher to get the plate off of the crank, and you could tell the plate had been slipping even more. It just has so much torque and the CVT is not even dialed in. No splines on the crank for the ramp plate is about the only thing I do not like about this motor platform when compared to a Mina. I know a lot of the high end CVT components for other motors do not have splined ramp plates, but there is not much clamping area where the ramp plate contacts the crank on these motors. I dont know how to fix the problem.  Anyway I decided it was time to take a look at the motor and see what to do about the high compression so I pulled the head to take a look. I had it in my mind that there would be something wrong with it, but it actually looked very good. No piston to head contact, no caved in piston, no aluminium bits floating around, good. Then I pulled the cylinder and expected to find something knackered but all seems good as far as I can tell. The only thing I can see is the crosshatch is gone in a few places. It could be because the ball hone I used on the cylinder is too fine of a grit, or I just dogged it toooo much! Anyway over the coming week or two I will see about getting the compression and the ramp plate issue sorted out.    |
|
|
|
Post by oldgeek on Nov 12, 2018 23:41:41 GMT -5
Also I have been thinking about the vibration source. I mentioned before about not being successful when trying to check the balance factor for this crank and piston combo. The crank is supposed to be used with bigger cylinders that have heavier pistons. I wonder if that is my vibration source. Since in theory the piston may be light. I wonder if I could add something like epoxy to the center of the wrist pin to add some weight to the piston?
|
|
|
|
Post by oldgeek on Nov 13, 2018 20:39:01 GMT -5
Gonna post measurements for the Compression ratio calculations here as I make them.
Head Gasket Thickness : No head gasket, several coats of copper spray
Head (combustion chamber) Volume : 7.67cc
Cylinder Bore : 50mm
Cylinder Stroke : 52.6mm advertised (piston moves 51.8mm)
Piston Depth Below Deck @ TDC : .5mm (average)
Piston Depth Below Deck (for volume measurement) : 5.15mm (average)
Volume Above Piston (as tested) : 7.67cc
Exhaust Port Depth Below Deck : 28mm
No, it's not a typo. The combustion chamber volume and the VAP as tested just happen to be the same.
|
|
|
|
Post by oldgeek on Nov 14, 2018 12:26:17 GMT -5
The measurements are posted above. I will try to do the math later today.
|
|
|
|
Post by 190mech on Nov 14, 2018 18:55:38 GMT -5
I got 12.77 uncorrected,7.34 corrected..Double check me though!!!  |
|
|
|
Post by oldgeek on Nov 14, 2018 19:55:35 GMT -5
I got 12.77 uncorrected,7.34 corrected..Double check me though!!! LOL! it took me two hours + but I came up with 17.38 uncorrected 9.85 corrected. I used the stroke of 51.8 in my calcumulations. EDIT: I also calculated using 52.6 stroke and came up with 17.63 uncorrected, but the corrected stayed the same at 9.85  I have no clue if I am right. I get so confused when it comes to numbers.  somebody! The suspense is killing me! |
|
|
|
Post by oldgeek on Nov 14, 2018 21:42:02 GMT -5
So if my further calculations are correct, increasing my combustion chamber volume by 2.33cc from 7.67cc to 10cc will bring my corrected compression ratio down to 7.44:1 which according to 90GTVert 's experience should be good for the street. FYI: this is the most and toughest (for me) math I have done in YEARS! |
|
After doing a bunch of launches and a burnout I could tell something was up with the CVT again. I pulled the CVT cover off and there were ramp plate guide pieces everywhere again. I got 4 miles out of the krap pair that came with the variator, and around 10 miles out of the Dr pulley guides I put in yesterday. 
somebody!