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decompresseion question..Need Help!!!


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I have a 1984 Honda xr500r, does anyone know what the correct settings are for the decompression cabels? one comes from the lever on the handelbars, and one comes from the kickstart. How do you adjust them correctly so the decompression works the way its suppose to? I'm so sick of kicking my bike over when they are not working right ๐Ÿ‘

can anybody help me? because I do not have the manual for this bike.

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Just disconnect that Kickstart one bucksaw. You don't need it and it's just one more thing to confuse matters at the moment. Take the cable off it and use the hand operated one till you get the thing to actually start and run correctly. You can then frig about with the other one later..The hand operated one just needs to be adjusted so when you pull the lever in the engine kicks over easily and when you release it it doesn't kick over easily..It's no more techo than that with that one..All you have to do then is make sure you have the starting drill worked out correctly when using it,,though I have to say their's a bit of variation in that between bikes even if it is more or less the same theory.

Edited by Horri
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alright I will do that then. Do I have to use the decompression lever on the handlebars when trying to start it? Because I know the start procedure as far as kicking it over slowly till the kickstart stops then I bring the kickstart back up and nudge it down about an inch more than I give it a good full kick. Does this sound ok? The handlebar lever for the decompression seems to work good. if I pull the lever and kick it over it kicks over really easy. If I dont its got tons of compression.

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Yep..Use it in conjunction with the starting drill you outlined..Get the engine into position using the Decomp lever and then kick letting the lever go at the same time or just do it the normal way..Bit of practice should get you the correct feel..You will know if you have the drill wrong as the thing won't kick over or when you attempt it the kickstart will come to an abrupt halt halfway through your kick..Kinda painful so take it easy till you get used to the feel..Wear some decent boots with a good solid sole on them,,not sandshoes (sneakers) or jandals (thongs).Have you got the bike actually running yet??..

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ok thanks. sounds pretty straight forward to me haha. and yes I have had the bike running but it will take me kicking it over alot times to get it going. even kicking it over perfectly with that procedure. This is what it is doing. it was 60 degrees out yesterday. I put it on full choke and kicked it over. it fires a couple times but fails to start. It keeps doing the same thing everytime I kick it over but it trys to start a little more and a little more everytime. finally after about 20 kicks or so it fires up and I can keep it running with the choke on. but with the choke on or off and the engine warm or cold if I let go of the throttle when its running it will die right away. I know the bike has great potential because it doesn't smoke and has great compression. whats your opinion?

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My opinion is it sounds like a pain in the butt like my 86 XR600 at the moment..Similar sort of problem to you but I believe their's something up with the Stator on mine. What I'd do with yours is make sure those Tappet gaps are correct ,they are critical for easy starting,,I'd also try turning the idle knob up a bit if it won't quite start then continue trying..Adjust it back down when or if it does start..Sort of normal procedure with just about all my 600's..Also make sure that Airscrews setting is right,,terrible thing to get at as it's I think under the bowls on a 500..I'm having trouble understanding this one and five eighths turns business with the Airscrew..I mean whats a full turn on that screw,,once around with the slot or twice around with the slot..(Perhaps someone can clarify that) That choke problem of yours sounds exactly what happens to my XR600 when I tried running a spare set of what I believe are 500 carbs on it yesterday,,I swapped all the jets over from the 600 carbs and it starts but only with choke..When I let the choke off it just starts farting as I ease it back then conks out..Haven't figured out why that'd be happening myself yet..I've reverted back to the 600 carbs until I get a new Stator then I may have a go with the 500 set again..Never ending crap..

Edited by Horri
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yea thats what I was thinking about doing next, checking the tappet gap. Its either that or a carb problem. Because I can ride my bike around my block with the choke on and go through all the gears and get the right carb to open up but when I try to ride it with the choke off, I cant get the powerband from the right carb. its just spits and sputters. Turn the choke back on and I got full throttle. Frustrating crap like you said.๐Ÿ‘ haha and as far as my air screw goes, I turn it in all the way and when my screw driver turns 1 1/2 times out I stop. Just as a rough starting point since I dont have a manual.

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Yep..Thanks for that..I've just been having a bit more of a think about this choke thing and I'm just wondering whether the XR500's use the same shaped main jets as the XR600.. My XR600 uses quite long hex bolt type jets whereas my XL's run kinda short screw head type ones. I recall a while back I tried running the longer type in one of my XL's and it just wouldn't run properly at all with them in..stated but just bogged when throttle was applied. When you got this bike had the previous owner been messing with the jets or changing the carbs around between the models at all ..I think we may have stumbled on a possible scenario with the XR500/XL600 carbs,,they won't work correctly in the fuel department with the longer jets..If you get the bowls off yours again can you take a picture of what sort of jets they are.. I've had a look at the parts fiches for all the models but they aren't clear enough or I believe accurate enough in the shapes to confirm this..If anyone else has a set of 500 carbs around maybe they could tell us what shape/length the mains are just to be sure..I can't be at this stage but if my spare set of carbs which may be either XR500 or XL600 (bought secondhand so I can't be certain what they are but will tomorrow as the carb numbers and models they go with are listed in the Clymer manual) won't run without choke and neither will yours then this could maybe be the problem..Lack of fuel in the bowls because of the wrong length mains...If you have a look on the right hand carb of your set just above where the bowl fits on you should be able to see a set of numbers..What are they..???

Edited by Horri
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hey horri, when I had my main jets out of my carbs last week they were the hex head jets about a 1/2 inch long from what I could tell just by looking at them. I am not sure to weather or not the previous owner messed with the carbs or swapped them for a different set. I sure hope not. I checked for the numbers you wanted off the right carb, here they are.

PH

51A[A]V67 this is what it looked like on the side of the carb. do these numbers match my bike? let me know what you think.

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Yep..Those numbers look about as close as the Clymer gets to 500 carbs. The numbers in the Clymer for 500's are PH60A,,PD50A..and PH51H so I 'd say they are 500s going by that last number. Still doesn't tell us whether the jets you have in there are the correct jets or not for a 500. As I say the previous owner of your bike may have stuffed up in jet shapes..Basically thats just a guess by me until someone else with a 500 can tell us precisely what shape the jets in their cabs are.. That set of carbs I tried the other day and thought were 500 carbs turn out to be XL600 carbs so I think thats the reason they wouldn't run with the XR600 jets I swapped into them other than with choke..XR''s use the hex type jets and are the wrong length jets for an XL600 carb...I'll get the XL screw head type jets for them in the next few days and try them again ..Don't know if I can really face trying to start it again till I do something about that Stator though,, may take a while to get one of them organised from god knows where in NZ..I'd prefer to buy new but can get a guy to rewind it if needed.. You need some 500 owner to verify whether yours are the correct type of jets or not in your bike..I can't as I don't own the RFVC model 500.

Edited by Horri
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alrighty thanks horri. I'll have to start asking around about those jets to get to the bottom of this dilema. this dual carb system is the most complication type of carburation I have ever worked on. its frustrating to me cause I build all different types of engines on a daily basis. I think I will have to just start being more patient with my bike since parts are hard to come by and not everyone has a xr500r haha. The headache begins...๐Ÿ‘

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OK...have a look at this photo

http://www.imagef1.net.nz/files/IMG_0066.JPG

The small round jet's a main from a twincarb XL600 carb

The hex one's a main from a twincarb XR600

The tube on the left has no jet in it

The tube on the right has one of the small XL600 mains in it..Huge difference in length and as I say if you have the wrong type in those 500 carbs of yours it will not run correctly. Pictures aren't to clear but you get the idea.

You should be able to purchase those small round ones in the correct size from a decent motorcycle shop..and by decent I mean a place full of old/oldish dudes thats been in business for a long time,,They generally have a box of jets hiding out back amongst the cobwebs. It also doesn't always need to be a Honda shop as I can get those small ones from a Kwaka dealer.. And dead right about the twins being a pain..give me single simplicity anytime...Pity no ones done the double to single converter yet for the twin models..I've looked at it but the variation and porting needed to make it work looked a little complex to me..and it varies between RFVC models so one size fits all won't work..An expert needs to look at it and figure the best method. Their's money there for someone though I have no doubt about it..

Edited by Horri
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thanks for pic horri. you are right about the length difference in those jets wow they are totally different. I can see why my bike wouldn't run right if the jets were the wrong ones haha. I'm gonna be pull my carbs off this week sometime. hopefully I can get everything right this time. oh and by the way, I'm gonna replace the little gaskets on the metal tube that connects the two carb bowls together, because mine started leaking. Do you know if I have to split both the carbs apart to do that? like disconnnect all the throttle linkage and all that good stuff?

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Can't be 100% sure on the splitting of the carbs..You may be able to get away with it by just loosening the two bolts that hold them together. Remove only the bottom one and then you may be able to flex them around the linkages without a total seperation..Those linkages sort of connect together on a type of push on nipple male/female type setup on one of the arms so just pulling that part may give you enough room to remove that tube and do the seals..Regards those jets,,Seeing we can't seem to get anyone here to confirm what shape jets the 500 uses it might pay to ask in Vintage,,Someone over their might know for sure,.Point them at that photo link I posted and see if you have any joy. Personally I believe it stands to reason they'd use those round type as the early XL600's..83-84 came with them so I reckon they'd have used them in the 84 RFVC500 as well. 86 XR600 is about the first time they started using those longer ones..According to my paperwork on carbs an 84 500 should be using a 108 in the lefthand carb, a 105 in the right and a 65 pilot..Those numbers are more in tune/close to number wise the round jets XL600's run..eg an XL600 from around that period has jetting of LH 108,, RH 105,, 65 pilot so same as your 500..Their's variations on that theme with the XL600's but you see what I'm getting at in the numbers . The XR600's start at about 118 stock and run up to about 130 and above in the hex head dept.

Edited by Horri
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alright thanks again horri. I will try that and see what happens. If I got split the carbs all the way then I'll have to just do it because I cant have the carb leaking all the time haha. So I will give it a try. Yea those jets are definitely a mystery. I'll keep asking around to see if find the truth about them. Just another frustrating day working on the dual carbs .๐Ÿ‘

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Good luck. I've located a good range of those smaller Keihin main jets about 2 miles away from where I live so I'm going to get a few sizes for the XL600 carbs I was trying to run on the XR600..Heres a URL if you fancy a look..They also stock some pilots,,just not all. I'll chuck in some parts place that does them in the States as well if you decide the shapes the issue. Those are correct dimensionally as I've measured them with the calipers and it's a match. Beats getting them from Honda..Probably take 3 weeks for therm to get them from lord knows where..possibly the same place I am but they'd whack on 100% markup even though the Honda dealerships about a hundred yards up the road from Cycletreads.

http://www.cycletreads.co.nz/products/501-keihin_jets/2958-keihin_carburetor_jets.aspx

http://www.pjmotorsports.com/keihin-jets.html?gclid=COuK2Ly_36ACFQxZbQod4CeACA

Edited by Horri
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hey horri I got another question for ya. I was looking at my intake manifold and noticed that it has that big rubber O-ring on it that kinda looks like mickey mouse ears. The problem is when I looked at the honda OEM diagram for my exact bike and it shows that it is suppose to have 2 separate round O-rings. Does this sound wierd to you or is that big o-ring normal for my model bike? I hope this isn't gonna be another problem, because I am already missing the heat insulator plate as it is. The original one was cracked in 3 pieces.๐Ÿ‘

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You mean this thing

http://www.imagef1.net.nz/files/IMG_0067.JPG

http://www.imagef1.net.nz/files/IMG_0068.JPG

Thats an XL600 one and the only spare one of them I have. Least I think it is without having a major rummage around in my boxes of stuff. I believe that on the inside of that is the heat insulator which connects to the head first and that thing above then goes on top of that and the carbs hitch up to it..I'll have a look at your bikes parts fiche at Service Honda if the servers working properly and see what I can make out. To be honest I've never removed any of those parts from any of my 600's so can't be sure what the makeup of that heat insulator thing is..and I have no spares of them to reference..I think I said before that if that insulators missing just go with it..I'll change that to you'd better locate one. What exactly is between the above part and your head then,,nothing??. Also what shape are the inlet ports to the head cause on the XL600s they are sort of two separate holes and if the above part was just bolted straight onto the head it wouldn't work as their is quite a gap of nothingness between those two ports.

Hmm yep, I've had a look at the 500 and 600 fiches of the head and you're correct the 500 is mildly different than the one above but it should be ok..That insulator thing you really need to locate..Wonder if someones swapped the heads around..or just that particular part.

Edited by Horri
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yea thats exactly what it looks like. The reason i am concerned is that I'm not sure it will seal to the head right and tight without that heat insulator plate. Because on the head surface there are 2 perfect circles that are machined flush. as you can see that o-ring on the intake manifold is just one big o-ring not 2 perfect circles. boy what did I get myself into haha.

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Yeah, know what you're saying and having looked at a spare head I have in the garage I can't see how it'd work with just that manifold bolted to it..Give me a few minutes and I'll take a picture of the head and post it..

http://www.imagef1.net.nz/files/IMG_0069.JPG

So if the ports on your head are the same as the above I can't see how it'd work with just the manifold posted further up the page bolted to it..I mean look at the gaps between the inlet holes .Their's no way that manifold would seal those..Least not in my mind anyway. I think it's a given that you need to locate one of those insulators..XL600 will possibly do the job..Twin carb XR600 may be different in the head inlet port dept so I don't know if one from them would be any good..I'll have to have a look at my head spares to be sure.. I have three or four heads some from twin carbies and some from single just not sure whether the twins are XR or XL..pretty sure they are all XL.

Edited by Horri
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