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97 cr500 jetting

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The Stock cr 500 jetting is a 170.

Mine is set up with a 180 and C-clip position 3.

This is a stock .060 motor.

Plug looks perfect with this setting.

Is this jetting jump sound normal or is it pointing to another problem?

Thanks!!!

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You didn't state your elevation and temperature, and that makes a difference.

If your plug looks good and the bike is running smoothly (no surging or coughing), then run it! Who cares what other people are running? If your bike has a surging problem just off of idle, then it may be sucking air in from somewhere, making your bike need richer jetting to compensate.

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elevation average 1500ft. temp 55 deg. no surging or blubbering. complete rebuild top to bottom .060 over, stock pipe with sparkarestor and boysen reeds. still wondering why this motor wants a 180 main... aways from the stock 170 jet. no airleaks. also this thing will not idle, have tried the air screw and choke lever turning to get correct idle but it acts like the kill button is hit when chopping the throttle. cant tell if the problem is too much gas or not enough to idle it. it will idle and sound great with a little tension on the cable. have been told this is common with the stock carb and to replace it with a pwk 39mm to correct problem and perform better. help. would rather iron out problem with stock carb if possible. thanks

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I'd check for a plugged pilot jet first.

Yes, your jetting sounds kinda rich--but again, if it runs right, so what? Also, some aftermarket jets aren't real reliable size-wise. Don't know if your running real Keihin jet or not, but just saying...

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would a plugged pilot let it idle good with a slight pull on the t cable or does it transition into another circuit as soon as a slight pull is applied. the owner before me had the freeplay taken out of the cable to have it idle and it sounded great and transitioned to wot well. although i know this is not the correct way of doing things. trying to dejib this setup!

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180 is way too big

seems big to me also but I have taken plug readings starting at the stock settings and worked up to the 180 with keihin brand jets. runs great but still have a idle issue. any ideas? also want to find out if the stock throttle cable will work with a keihin 39mm pwk d slide carb when I do get fedup with the idle problem.

Edited by fusebox
add more info

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many think they know how to jet a bike. very few actually do....... i can assure you Deebz is not one of them. forget what the books say, forget what any dimwit around here says. use what the bike needs. i seized mine up at 4'500 90deg air temp with 168. i know for fact it would need atleast 180 at 1,500...... which happens to be way different than what the book says. if you ever ride sand dunes you better have your ducks in a row or youll burn that sucker down fast. takes about 4 seconds and your new piston goes up in smoke

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woods rider only. this bike will never see sand again now that I have rescued it from the sandsquid before me. luck for him, he did have a fat jet in it. just trying to get it dialed in for the coast range and my peace of mind.

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buy handful of jets and get to work. some dude on the other site swears he runs 168 at sea level dunes but i toasted mine at 4,500 with 168. hard for me to give any concrete starting point because every engine might not be the same. first post you said its running good. just leave it as is

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Seems like you have a cable/idle setting problem. I can't offer any quick solution but my standard carby works fine and idles OK. (2001 model, new top end, second oversize, shaved head)

I know a common upgrade is to change carby but a standard one can and should work.

In my case I reset the float level 1mm lower than standard, cleaned it, tried a few jetting combinations and ended up with a good running 500.

I'd investigate the choke/idle mechanism first, then your cable/tension. Maybe the cable spring needs replacing.

IMO, if you just use looking at your plugs to set your main you will mostly end up too rich. I cut my plugs open after a plug chop and measure the carbon line at the base of the porcelain. This is usually a good indication of how the main jet is working (google or search up on this for more detail)

I find the plug shell surface a better indicator of overal jetting. That circle of flat 1.5mm thick steel is usually mid brown after an hour or so when I have the jetting pretty close.

FWIW, at sea level and 60F I am running a 172 main, clip 3.5 (using a half clip .5mm shim/washer under the actual clip) and one step larger pilot(58) The needle is the 1369. Standard is 1368. It also ran quite well with the 1368 in clip 3 or 4.

I use a 178 when I go to the sand.

Let us know how you get on. As suggested by others, experimenting with

some jets/needle combos is the best way to learn and re jet, takes time though.

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it will idle and sound great with a little tension on the cable.

Lol, I just replaced my PJ28L carb with a brand new PWK A/S on my '98-cr250, and thats the first problem I encountered, I thought it might be a stretched cable.

But I dicked around turning the air-screw half turns and using the idle screw, and ended back with JD's settings of 1.5 turns out and it idling perfect.

One of the things I noticed before I got it to idle was my crankcase breather tube was plugged, dunno if that made a difference. Haven't checked the colour of my new plug yet.(seems to be running crisp and clean)

I had lots of reasons for buying the new PWK, alot of it taking the guessing out of that power jet solenoid on the pj, and subtracting the $80 a JD kit was gonna cost me. Part of my long story is I had a shop hint I almost cold seized a new piston, which I know isn't true.

I live on the wet coast too, north of you, and I think the humidity in the air makes our sea-level jetting unique.

edit: mine was surging and blubbering a little before the swap.

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got the stock carb dialed in except for the continueing idleing problem. this thing will not even come close to idleing. have been thru the carb several times now and being fed up with this problem, I ordered a 39mm pwk and told by many that when I get this one dialed in that I would be extreamly happy with my decision. thanks for the input all!

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swaped out the pj for a 39mm pwk. ended up with a 185m, 55 slow, clip at midpoint 1.5 air screw and this thing rocks! recommend this upgrade to anyone running out of things to do with thier bigbore. way easier to start, more response and power all thru entire range:thumbsup: coast range riding, 1000-2000', 45-60 deg.temps

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