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Post by niz76 on Apr 19, 2015 0:13:53 GMT -5
Seems like it may be a carb tuning issue... What main jet is in the carb that you bought? It may not be jetted properly for "plug n play". Is the carb the same size as stock? An air leak will affect performance tremendously as every little thing affects the air/fuel ratio... Even though it may Rev on the stand, the carb may still need to be tuned properly... A little trick I use is to use that snorkel in the airbox as a tool to help you identify if you're too lean or too rich. Taking the snorkel out will allow more air therefore leaning the mixture. Putting the snorkel in and maybe even restricting it some with a loosely wadded paper towel would richen the mixture... Hopefully you can feel a difference in performance and know which way to go- upjet or downjet. With the right carb tune you'll probably get the power back!!
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Post by Silar on Apr 19, 2015 12:05:30 GMT -5
Seems like it may be a carb tuning issue... What main jet is in the carb that you bought? It may not be jetted properly for "plug n play". Is the carb the same size as stock? An air leak will affect performance tremendously as every little thing affects the air/fuel ratio... Even though it may Rev on the stand, the carb may still need to be tuned properly... A little trick I use is to use that snorkel in the airbox as a tool to help you identify if you're too lean or too rich. Taking the snorkel out will allow more air therefore leaning the mixture. Putting the snorkel in and maybe even restricting it some with a loosely wadded paper towel would richen the mixture... Hopefully you can feel a difference in performance and know which way to go- upjet or downjet. With the right carb tune you'll probably get the power back!! Same carb size, but the new one is a KeiHin. One thing I started thinking last night.. I didn't check the float. When I'm on the scooter and give it throttle about 1/4 to 1/2, the bike has power and seems to accelerate fine up to a certain point, then I need to give it more throttle to go faster but anything above 1/4 to 1/2 or so just doesn't give the bike any more power. The throttle cable and linkage work fine. There's no back firing on decel and it doesn't bog down like it's going to die or anything. I did try putting the old carb back in to see how it would do, but it is so gunked up it would barely even accelerate at all so I put the new carb back in.. I did check TDC and that is good. I wanted to make sure it somehow didn't jump a tooth or something like that. Chain is tight and the tensioner is doing it's job nicely. Last night I pulled the variator, took it apart and cleaned it real good. I should have taken pics, but the rollers look okay and didn't seem to have any flat spots, but had some discoloring. I also pulled the bell housing off the clutch to inspect it and the clutch springs are tight and also the main spring requires significant force to open the pulley to where I thought I wouldn't be able to open it by squeezing with my hands. I'm just trying to get this scooter to run decently so my wife and I can ride our scooters together, but this thing is becoming more of a pain than I ever thought.
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Post by Silar on Apr 19, 2015 14:52:19 GMT -5
I checked the float. Honestly not even sure where it needs to be set at but it looks like it may be set too high allowing more fuel in. The first pic shows the float height. The second pic shows me pushing the float down. Doesn't travel much at all. Looks like the carb has an 85 main jet. Anyone know where the float should be set? I figured midway, but can't really tell by the line on the float itself.
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Post by Silar on Apr 19, 2015 15:17:11 GMT -5
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Post by Upgrayedd on Apr 19, 2015 16:59:13 GMT -5
that looks very rich. that's too rich on idle, and too rich on main jet as well, imo.
niz is good - niz is wise - getting that carb in tune will help you _a lot_. whether you choose to install a smaller main jet, or open up airflow to lean it out, is up to you.
i can see what looks like a timing mark on the strap. it may not even be, its hard to see its all so dark, but if thats the timing mark on the strap then the timing looks OK.
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Post by Upgrayedd on Apr 19, 2015 17:01:07 GMT -5
I tend to stay anywhere from what it shows as 'best' and from there toward a bit rich, since these are air cooled engines the fuel does aid in cooling the engine a bit. Leaning it out to where the porcelain stays white (which would be acceptable in a liquid cooled scooter/mc plug) would run too hot for my liking, and risk engine failure/damage. a nice chocolate color on the strap, with a bit of black on the idle turn (the flat base) and black a couple threads down the side, with the timing mark somewhere in the middle of the strap turn, porcelain looking a bit tan (but not tan from running too hot, that is different) that's about what they show in that 'best' one. a bit rich on idle is OK in my opinion.
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Post by Upgrayedd on Apr 19, 2015 17:06:02 GMT -5
ps it is quite possible the keihin carb came with an 85, and the original carb may have had a smaller (my 49cc came with an 81 main jet stock)
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Post by niz76 on Apr 19, 2015 17:22:22 GMT -5
that looks very rich. that's too rich on idle, and too rich on main jet as well, imo. niz is good - niz is wise - getting that carb in tune will help you _a lot_. whether you choose to install a smaller main jet, or open up airflow to lean it out, is up to you. i can see what looks like a timing mark on the strap. it may not even be, its hard to see its all so dark, but if thats the timing mark on the strap then the timing looks OK. Aww shux thanks Upgrayedd! Yep looks rich- Upgrayedd hooked u up pretty good with some visual reference to help u get that carb in tune! Get a couple smaller main jets and slowly drop down checking your plug/feeling performance with your "butt dyno". Can be a bit of a process but a lot of melted pistons lately (me included) showing how important carb tuning is!!
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Post by Silar on Apr 19, 2015 17:30:46 GMT -5
What about the float? Where should it be? See my previous post with pics of my float level.
Also, How hot should the valve cover be? For me, it is way too hot to even touch just letting it idle to temp.
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Post by Silar on Apr 19, 2015 20:39:15 GMT -5
Adjusted the float to lower the fuel level a bit in the bowl and same problem. I did try taking off the breather tube to open air into the air cleaner and plugging it also to restrict it. There were noticeable differences, but what would be expected. Didn't change any power at all. I figured even with an 85 jet, removing any air restrictions prior would have leaned it out a bit but it still didn't have any power under load. I think the carb is fine.
I'm really starting to lean more towards a compression issue. Maybe piston rings, valves not seating, valve stem seals or something like that.. I don't see any smoke, but I took the vent hose off the breather fitting on the valve cover and there is air pulsing out of it at a constant rate. Also, I cleaned the spark plug real good and put it back in before I did the testing and afterwards, pulled the spark plug again and it was black. Smelled like oil. I don't have a compression tester to check but I'm really thinking that may have been the cause all along.
Would that cause it to not have any power? No joke, I can literally hold the throttle at WOT and with my feet down, keep the bike from moving.
On a side note, I decided to throw the old carb into my berrymans carb cleaner so I took it apart. It was crazy nasty! Obviously why the bike wouldn't run at all with it.
Anyone want to recommend a BBK? Also what could I get by with for now if I go with a BBK? Do I need to upgrade the exhaust or can I leave that for now until later?
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Post by Fox on Apr 19, 2015 21:32:56 GMT -5
The valve cover sits right on the part of engine where the gas goes BOOM BOOM thousands of times a minute. That's the hottest part of the engine. It's normal don't worry about it. That plug being so black it seems that you need to open up the air flow some. You can remove the snorkel plug (first pic) you can remove the little rubber tube inside the air box cover, and you can actually drill holes in the air box cover even. When all is said and done you want the brown spark plug.
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Post by Silar on Apr 19, 2015 21:42:23 GMT -5
I took the whole snorkel off. It didn't make a difference for the plug color and I'm pretty sure it's not fuel on the plug. Smells and looks like oil once I cleaned the plug and ran it for a bit and checked afterwards.
I bought a BBK kit with everything except the carb and exhaust. I figure if I need those, then I'll buy them once I get the BBK in and test it.. Also bought a new CDI so I can make absolutely sure it's not that.
I hate to keep throwing money at this thing, but I really want to make this darn thing work!
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Post by Upgrayedd on Apr 20, 2015 11:52:36 GMT -5
I took the whole snorkel off. It didn't make a difference for the plug color and I'm pretty sure it's not fuel on the plug. Smells and looks like oil once I cleaned the plug and ran it for a bit and checked afterwards. I bought a BBK kit with everything except the carb and exhaust. I figure if I need those, then I'll buy them once I get the BBK in and test it.. Also bought a new CDI so I can make absolutely sure it's not that. I hate to keep throwing money at this thing, but I really want to make this darn thing work! it's not going to make a difference in that plug's color, that plug is already blackened. that plug is either carbon fouled, oil fouled, or both. you need a brand new plug to take a new reading. carbon fouling means its running very rich, you've got 3 people in this thread who are experienced in working with engines telling you it's running rich. but if you're satisfied with that and feel the carb is fine, that's your call and no offense meant. im just pointing that out so you can weigh that into your decisions. it might be oil fouling as well. there's two ways oil is pulling in there, either past you rings or through the valves. you're going to have to pull the top end to get a look if you suspect oil fouling, you can start with a compression test if you have the tools. air pulsing out of the valve vent is to be expected. the engine has a pretty small crankcase, and every time that piston goes up and down, there's a change in the volume of air in that crankcase. of course blowby would also exit via the vent, but even without blowby, the vent will have pressure changes in time with the engine running. you mentioned the clutch. maybe the clutch could use an adjustment. once the clutch is fully engaged at takeoff, it stays engaged until you stop. it wont affect your shifting up at higher speed.
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Post by Silar on Apr 20, 2015 13:01:00 GMT -5
Thanks for the reply. I used a torch and burned all the carbon and oil off the plug before putting it back in so I could test it clean. Looked like it did when I bought it last week.
I'm not disregarding what everyone is saying. No reason to get testy because I found something wrong other than the carb. I do have mechanical experience. I've rebuilt my Land Rover engine and the 302 in my 1982 ford f100. I've also done a complete frame up on my 1984 v65 Magna. I greatly appreciate the help. I thought it was too rich also.
I'm pulling the head when I get home from work today to inspect the valves, piston, rings and seals.
I planned on buying a bbk anyways and id rather have it on hand. After going through everything I went through, on this scooter, there's definitely something other than the carb.
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Post by Upgrayedd on Apr 20, 2015 13:30:57 GMT -5
ahhh the old v65. fastest production bike of its time ^_^ my new neighbor has a v45 that's making a heck of a racket. sounds like maybe the timing chain guide is gone and its slapping around in there. that or a cam issue :/
sounds like youll find the issue in that scooter engine before long
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