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Post by 90GTVert on Nov 1, 2023 13:25:16 GMT -5
I put the 122 main jet that came with the carb in the lathe and drilled it with a 2.5mm bit. That’s in the carb now. Whenever the wind calms down I’ll see what happens with it. If that doesn’t work then maybe I’ll take the main jet out totally and find out if it runs. 🤷♂️
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Post by Lucass2T on Nov 1, 2023 16:32:43 GMT -5
I think you said you've fiddled with powerjets before. Myself i never have but I believe they become handy in these kinda situations where you run out of main jet.
Is the polini fitted a powerjet or does it just have a blank port?
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Post by 90GTVert on Nov 1, 2023 17:25:14 GMT -5
I think you said you've fiddled with powerjets before. Myself i never have but I believe they become handy in these kinda situations where you run out of main jet. Is the polini fitted a powerjet or does it just have a blank port? Only the Lectron. The Polini PWK is a non-power jet version.
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Post by ryan_ott on Nov 2, 2023 8:58:22 GMT -5
That thing was a handful with the 86 I couldn’t imagine how difficult it is to keep it down now. Wheelies are why I switched to the MetRuck I just couldn’t keep the front down on the Zuma while giving it full send. Flip over and eat sh*t!
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Post by 190mech on Nov 3, 2023 2:47:36 GMT -5
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Post by Lucass2T on Nov 3, 2023 5:15:04 GMT -5
Thats an interesting take on carb tuning. I think this method may work well for beginners. Although I would decribe the method of tuning the main jet a bit more in a objective way instead of relying on a description of how it should sound. I always spot a lean main jet by finding the bike feels strongest at 9/10 throttle. When you go to WOT it will hold back slightly. A main jet which is too big will show strong drop of power when you slightly roll back the throttle. From 3/4 throttle to WOT power increase should be linear to throttle increase.
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Post by 190mech on Nov 3, 2023 5:31:23 GMT -5
A G Bell wrote about this tuning method (page 104). I have never tried it,but can say that the jet needle/needle jet are often forgotten ,causing tuning nightmares! The first RM250's had bad detonation causing piston failure, we tried a lot of jet work to no joy,,Suzuki came out with a bulletin saying to change the needle jet to a Q-6 and sure enough that cured the problem...
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Post by 90GTVert on Nov 3, 2023 5:44:13 GMT -5
As soon as I read the stuff about removing the main jet to look for the needle and needle jet first, I knew I recognized it. This is not a conventional tuning process that many follow. I believe you told me about it long ago... at least someone on the forum did. That is from an article by Don K. Courtney called "Jetting - Getting The Most Out Of Your Bike". I can't seem to find the original article. I know it's been around since at least 2010. Searching for the author doesn't bring anything up for me aside from a facebook page that looks like it's possibly the author... based only on a dirtbike profile pic and the only person that comes up for that name. Unfortunately there are only a few brief posts that are non moto related over the course of the user's history and they didn't fill out any work related info that could help find if it was in a magazine or a webpage or how it was originally posted. There's a scribd document that contains the same text, however it appears to be screenshots of a Lambretta page where it was reposted. Since all I can find are reposts, I'm going to do the same in the Tech Library. It's an interesting idea that I think some will like to read about. I'd rather link to the original to be as respectful as I can to the author, but that's not happening right now. 49ccscoot.proboards.com/thread/31687/alternative-method-figuring-carburetor-tuning
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Post by 90GTVert on Nov 3, 2023 5:56:55 GMT -5
A G Bell wrote about this tuning method (page 104) It begins on page 136 for me in the hardcover 2nd edition, but here's an excerpt : " When an engine has been extensively modified, I prefer to begin testing (after ensuring that the float level is correct) with the main jet removed. If the engine will just run at part throttle, but floods as the throttle is opened, then the needle jet is large enough. However, if you find that the engine keeps going at three-quarter to full throttle you can be sure a larger needle jet is needed. Note that this test should be done with the needle lowered to the No. 1 (ie lean) clip position.
After you have determined a needle and needle jet combination that is too rich, you can then try various size main jets until you find one that allows the engine to run reasonably well at full throttle. Don't worry about throttle response or acceleration for the time being. Carry out this test with the needle raised to the middle clip position."
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Post by 90GTVert on Nov 3, 2023 8:35:31 GMT -5
I tried the 2.5mm drilled main jet yesterday. Avg EGT at 60MPH in acceleration runs was 1252, but it did get hot at the end of 1/8 mile runs. Acceleration times were a little slow, but more was going on. When I checked the video, it was revving higher. On the way home I was holding it around 1/4 throttle and it approached 1250 EGT so I changed throttle position and it felt a little off. I then went to WOT and it felt like a lot of slip and then even lower throttle made it feel like it was slipping. Stopped or at low speed it felt sluggish like it was low on power or more like there was a clutch or CVT issue. I was thinking that maybe my belt finally started giving up. I pulled the cover this morning and found that the vari and cover had made contact. I removed it with a rear jet to see if it the but was loose, but it was tight. The crank doesn’t seem to have any play to cause the contact. Other parts like the ramp plate, fixed half and spacers showed minor wear from spinning against each other and you can see grease with metallic debris on the case. The rear seal in the variator looks like it moved a little and there is grease splatter around it. I pushed the seal back in, but I assume it’s bad. It’s a 22x29x4. I’m not sure if the swap from a metal garter spring to an o-ring inside of the variator has anything to do with it, but the o-ring still looks good and I’d think the rear seal should do it’s job regardless. It ran just fine with the o-ring for a bit so I wouldn't think it was doing anything too bad, but Polini chose a garter spring for a reason I guess. I’m not really sure what caused the initial rotation that allowed parts to chew on each other or the seal moving. I was looking for a 1.5mm diameter x 22mm garter spring with no luck. Similar springs are used in A/C fittings and oil/shaft seals but I looked at auto parts places and they're standard sizes that don't seem to match up and I have no idea how you'd figure out what size garter spring is in a certain oil seal. I can’t find a 22x29x4 oil seal that can arrive in short order and without large shipping charges. This is going well. Considering buying a new vari, but that seems ridiculous over a seal and spring and minor damage of the ramp plate from spinning since I think it’s OK otherwise.
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Post by 90GTVert on Nov 3, 2023 12:01:32 GMT -5
The seals I can get in maybe 3-5 days if I'm lucky for $33 for 3 from PartZilla (Suzuki 09285-22001). Local dealer (50 miles away) says that part has been replaced. The replacement is 21x29x4. I didn't even ask if they had that in stock. No thanks.
The garter springs I'm still not seeing. I can get standard sizing from McMaster-Carr that may or may not be close enough to work as intended. $16 for 1.
So basically $50 for a seal and 2 spares and a spring that may be wrong. Not even sure I'm gonna bother with the spring. May just rely on the o-ring. I don't know that anything is totally necessary inside of the variator. Malossi's didn't use anything other than the inner and outer seals without issue. Hmm. Maybe I should see if Malossi's seal just happens to be the same size before I pay expedited shipping rates for standard shipping time. EDIT : Nope. Malossi's are both 22x28x4.
I could put the Malossi variator on to do carb stuff, but then I've gotta figure out where the weights need to be with the Polini spring (prefer to keep the stiffer spring) and where the spacing should be and I'll want the Polini back anyway because it seems slightly quicker. 🤦♂️
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Post by 90GTVert on Nov 3, 2023 15:42:52 GMT -5
Ordered the seals and nothing else. I’m gonna switch to the MultiVar for now. I already made CVT changes anyway so I was going to have to bolt the 28mm back on after for a direct comparison anyway. Possible cause. Maybe just an effect. One of the spacers behind the variator was chewed up with an obvious ridge in the center so I found 2 washers that came out to 4mm thick and cut them to the right ID.
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tysta
Scoot Member
Posts: 74
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Post by tysta on Nov 4, 2023 0:29:19 GMT -5
If you lean foward you should be able to control the wheelies no problem. your weight should be enough to keep it down. 🤣 You’ve obviously never rode this thing. I sit all the way up on the seat, lean forward and get the front suspension compressed from my weight and when it’s right just rolling in too quick makes me get back out of the throttle. I know it ain’t the fastest scooter around, but when the tune is working I have had to get out of it because it would loop itself from a 25MPH roll. I don’t like big wheelies and usually don’t get the wheel up more than a foot because I find it scary even at that, but I have accidentally done them before. Granted, I’m usually in my normal riding position on the back of the seat when I’m doing 25-30MPH power wheelies but I’m not even using all of the throttle before I get back out of it sometimes (with the 28mm… haven’t really tried with this). I believe ryan_ott could vouch for me on this. If not, I’d gladly let him hop on it next time he’s around and find out how easy it is to keep down. He rode it with the 86cc and the wheel would come up a little with that and I could launch that most of the time with quick WOT no problem as long as I kept my weight up front. Well I do understand what you have there. No offense still a basic malossi engine, without more changes and adjustments they don't make crazy power. What's your 0 to 60 right now.
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tysta
Scoot Member
Posts: 74
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Post by tysta on Nov 4, 2023 0:32:46 GMT -5
Ordered the seals and nothing else. I’m gonna switch to the MultiVar for now. I already made CVT changes anyway so I was going to have to bolt the 28mm back on after for a direct comparison anyway. Possible cause. Maybe just an effect. One of the spacers behind the variator was chewed up with an obvious ridge in the center so I found 2 washers that came out to 4mm thick and cut them to the right ID. Avoid using 2 washers They will case some stupid wear between them Get a steel bar and cut it on the lathe. Also the spring you need does not need to be that exact size it can be bigger then you cut to the size you need. In case you still need let me know I have them.
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Post by 90GTVert on Nov 4, 2023 6:13:51 GMT -5
Well I do understand what you have there. No offense still a basic malossi engine, without more changes and adjustments they don't make crazy power. What's your 0 to 60 right now. Best I've ever done is only 7.0. Ryan is well ahead of that on his also still pretty basic Malossi engine. My best 60fts are 2.1x and most of the time I'm 2.3x. There's time to shave if it could be launched with quick WOT and without a bunch of slip but I'm still a big dude so it's never gonna be a rocket. The scoot and I weigh as much as some liter bikes and their riders. Basic or not, the scoot is like a 4x4 stance with a high center of gravity that puts the center of mass far from the traction point of the tire and I'm sure my suspension is all wrong so it's pretty fun to ride... and it is out there in the world. Most of the crazy fast stuff that I see sits in garages, dyno rooms and occasional track events.
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