Posted January 31, 201213 yr Hi all. i know this has been discussed at length but i can't get an answer to my question jn my searches. do if anyone could help that would be great. is there anyway to tell if one of the diaphragm's in the mikuni carbs on my virago xv 500 are not performing correctly. My bike is topping out at 60 mph so i'm trying to figure out if its a carb problem or electrical problem. the bike runs perfectly from 0-55 mph. Thanks for and help.
January 31, 201213 yr Hey mate a good way of checking the diaphrams is to get your carbs, look in the top (inlet from where your air filter pipes connect to it) and you will see a black tube with a needle sticking out of it, push the black thing back wards and let go, you should hear the diaphrame sucking in airand it should be a bit slow on returning (but not too slow mind) to its starting possision. I just tried to see if i had and pics of the top of my carbs to show you the black tube thingy but i havent lol sorry Have you tried using some carb cleaner? may have a bit of gooo in there or some thing.
January 31, 201213 yr Author Cheers noise. I'll try that. just hate the thought of taking the carbs out. they are not easy get back in. Its only 6 months or so since i cleaned them, could they gum up that quickly. Have you ever come across an electrical fault causing a bike to loose after 55. its very weird, the bike runs as normal up to that speed. Thanks for the help noise.. I digress, how you finding the karate? what style you doing? i ask cause i used to do it up until the kids came along
January 31, 201213 yr You wont need to take the carbs fully out mate just up till the point where you can get your finger into the tops, so in my case for example on the dragstar id need to take off fuel tank, then the air filter and thats it. should be the same with the virago i would think. my carbs are out at the mo as funny enough ive just had to change the diapham needles on mine so i will take some pics for you, and up loasd tomorrow if you like? The Karate is going well, only been going for 12 weeks going for my grading in mid feb, as for the type of karate i will have to let you know as i cant for the life of me remember how to spell it I only started due to leaving tha Army due to an injury to my back and my legs started to seize up and it got to a point where i could only walk for 15 mins in town before id had to sit down and let my legs recover. So now im more active im in less pain than i was but it never gose away, but the Karate helps alot with the stetching etc.
January 31, 201213 yr Author Tried that noise. the virago is different in that i can't get my hand to the top of the carbs cause the frame gets in the way. I put carb cleaner in so I'll see if that makes a difference. TBH I'll be surprised. U'll probably laugh but you prob need something like yoga to help with your back.
January 31, 201213 yr Moderator http://www.google.co.uk/webhp?sourceid=toolbar-instant&hl=en&ion=1&qscrl=1&nord=1&rlz=1T4GGLL_enGB401GB402#hl=en&cp=23&gs_id=l&xhr=t&q=carb+cleaner+and+rubber&pf=p&sclient=psy-ab&qscrl=1&nord=1&rlz=1T4GGLL_enGB401GB402&site=webhp&source=hp&pbx=1&oq=carb+cleaner+and+rubber&aq=f&aqi=&aql=&gs_sm=&gs_upl=&bav=on.2,or.r_gc.r_pw.,cf.osb&fp=d8b2093a804d7feb&ion=1&biw=1024&bih=540Tell me you didnt squirt carb cleaner at anything rubber!
February 1, 201213 yr Author God no. i used the stuff that you put in the fuel. if that does'nt clear it out I'll take the carbs out and clean them again. I read a thread last night about a guy with the very same symptoms and it turned out to be a faulty wire in the harness. I'll look for the link tomorrow. that's a great link Airhead thanks for that. i have it saved in my bookmarks.
February 1, 201213 yr Hi Mate here are some pics for you to do a quick check on the diaphragms to see if they are working, Diaphragm fully out Diaphragm pushed in half way Diaphragm pushed in When you release the diaphragm you should/will hear it suck in air, that means its working.
February 1, 201213 yr Author Cheers noise. i'm gonna take the carbs out at the weekend and check them out.
February 5, 201213 yr i have seen this on loads of forums and this seams to be a very common fault on the xv535 yet no one knows the answere to it i have the same prob done all the above but bike is still the same its like no fuel at the top end of the revs bike is fine upto 55 60mph but after that no go
February 5, 201213 yr Author Thanks for that neversaydie, can't read it though. can you summerise ? the eyes ain't what they used to be :-)
February 6, 201213 yr POOR RUNNING OR NO POWER AT HIGH SPEED FIRING INCORRECT air filter restricted, clean or replace spark plug fouled, defective or worn out spark plug cap or HT wiring defective spark plug cap not in good contact incorrect spark plug, wron type/heat range igniter defective ignition coils defective FUEL/AIR MIXTURE INCORRECT main jet clogged, clean the fuel tap filter, float bowl, jets and orifices main jet wrong size throttle shaft to carburetor body clearance excessive air bleed holes clogged air cleaner to carburetor boot poorly sealed, cracked holed, or loose clamps fuel level too high or too low, adjust floats fuel tank air vent obstructed carburetor intake jopints loose, carcked, broken, torn or loose clamps or bolts fuel tap clogged fuel line clogged COMPRESSION LOW sparl plug lose cyclinder head not sufficiently tightened down improper valve clearnace cylinder and or piston worn piston rings worn piston ring to groove clearance excessive cylinder head gasket damaged cylindrr head warped valve spring broken or weak valve not seatin properly KNOCKING OR PINGING carbon build up in combustion chamber incorrect or poor fuel quality spark plug heat range incorrect improper air/fuel mixture MISCELLANEOUS throttle valve doesnt fully open clutch slipping timing not advancing engine oil viscosity too high brakes dragging
February 6, 201213 yr Author That must have taken ages to type, thanks very much neversaydie. It's an excellent post. It should be made a sticky. I had a little luck with my bike today. I took the baffels off the exhaust and when for a ride. Low end power was better and so was the top end speed. Gonna try and clean out the baffels and see what that does.
February 13, 201213 yr That must have taken ages to type, thanks very much neversaydie. It's an excellent post. It should be made a sticky. I had a little luck with my bike today. I took the baffels off the exhaust and when for a ride. Low end power was better and so was the top end speed. Gonna try and clean out the baffels and see what that does. realrayzor have you had any luck in fixing your bike yet
February 13, 201213 yr Author No not yet. have'nt had time to take the carbs out. I'll get to it this week and let you know if cleaning the carbs sorts it.
February 14, 201213 yr Author realrayzor have you had any luck in fixing your bike yet well i took the carbs out and low and behold one of the diaphragm's wasn't't sucking. When i took it out itcame apart. so i put that back together andwent for a quick spin. it seem's to be alot better. i'll be going into work in the morn so i can open her up and see how she performs. fingers crossed it's sorted. I'll post in the morning how it went.
February 14, 201213 yr Author Bike back to her old self,,, The bike is like a superbike compared to what it was. She is pulling out to 75 mph no problem. Inbed79: i'd reccommend taking your carbs out and checking your diaphragm's. Check for any holes and defects or replacing them altogether.
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