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ViragoTechForum.com XV750 HELP ME PLEASE (solved)

#1:  HELP ME PLEASE (solved) Author: john122hum Post Posted: Thu Aug 12, 2010 5:54 pm

help me please I had a constant popping and backfiring through my exhaust so i adjusted the valve clearance. I used the .004 feller gauge on the intake valve and the .006 feeler gauge on the exhaust valve just like the Clymer Manual send. I put the bike back together and started it up only to discover now my valves are VERY loud clacking away. bawling what could I have done wrong i?

Last edited by john122hum on Sun Aug 15, 2010 7:14 pm; edited 1 time in total

#2:  Re: HELP ME PLEASE!!!!!!!!!!! Author: terrip Post Posted: Thu Aug 12, 2010 6:05 pm

Was the engine cold when you adjusted them? And did you turn the crank so that each cylinder was at TDC when you adjusted?

#3:  Re: HELP ME PLEASE!!!!!!!!!!! Author: john122hum Post Posted: Thu Aug 12, 2010 6:10 pm

yeah it was cold have not riden it in a few days. turned the crank to the T mark for the the rear cylinder and the I mark for the front cylinder.

#4:  Re: HELP ME PLEASE!!!!!!!!!!! Author: terrip Post Posted: Thu Aug 12, 2010 6:23 pm

Sounds like you timed it properly. How long did you let it run after the adjustment? Air cooled engines expand and contract a lot so the valves may make more or less noise depending on how hot the engine is. For example, my Virago tends to get a little noisy when it's hot, but it has 20,000 miles and I don't think it's ever had a valve adjustment (it's on my list of things to do). My Honda's valves are always noisy no matter how hot or cold the engine is and I recently adjusted them and it made no difference in how loud they are. The noise you're hearing may also be the cam chains. If the noise is really troubling you, I would recommend double checking them just to make sure. Now that you know how to do it, it wouldn't take very long. naughty

#5:  Re: HELP ME PLEASE!!!!!!!!!!! Author: terrip Post Posted: Thu Aug 12, 2010 6:30 pm

But to analyze your symptoms, popping and backfiring, especially on deceleration would indicate something amiss with your fuel/air mixture so the culprit is most likely your carbs. The popping and backfiring indicate that your fuel/air mixture is too rich so when combustion takes place, excess fuel gets put into the exhaust where it backfires. If it's a problem you haven't had before some junk probably got into one of your jets, especially if you don't have an inline fuel filter. If it's been an ongoing problem, you might want to clean them well and check your jets to make sure they're the proper size. If you have an aftermarket exhaust that can lead to fuel/air issues as well. Seafoam works wonders!

#6:  Re: HELP ME PLEASE!!!!!!!!!!! Author: john122hum Post Posted: Thu Aug 12, 2010 7:35 pm

thanks for the help terrip. it does have after market exhaust ill try the sea foam. so another question. when installing the valve covers i have stripped one of the screw holes. it wont get tight it barely snugs up. how do i fix this? if it doesn't leak should i even worry about i?

#7:  Re: HELP ME PLEASE!!!!!!!!!!! Author: terrip Post Posted: Thu Aug 12, 2010 7:55 pm

I'm not too familiar with the earlier Viragos, but I assume they're similar to the later ones. Are there only 2 screws holding the cover on? If so, I would definitely do something because it could potentially leak at some point, or get dirt in there, or it might come loose which wouldn't be a good thing.

With older bikes it's easy to strip holes because you're putting a steel bolt in an aluminium head and there's usually corrosion on both parts which makes you unsure of when it's tight and then poof! you stripped it. I did something similar to the carbs on my Honda and I tapped the hole with the same thread, but I tapped it deeper so I could just put a longer bolt the same size in the hole. If you feel how deep the hole is and compare it to the bolt you can tell if there's any extra depth to work with. You could also try re-tapping the hole with a different thread, but that can be tricky sometimes. In either case you would have to be really careful to not get any metal bits down in the head by stuffing a rag or something in the hole.

If you're not too concerned you could also use thread locker to make sure the bolt won't back out, but make sure you use the temporary stuff or you'll never get the bolt back out. The cover might not be super tight, but the bolt won't vibrate out.

In many cases with aftermarket exhausts the mixture becomes too rich so you might need to lean out your jets. Finding the right jet is a trial and error process, and can be tedious, but it's easy enough to do. Most people feel the need to put in richer jets, but they're usually wrong. I've never done it on a Virago other people might be more helpful with what sizes might work.

Good luck!

#8:  Re: HELP ME PLEASE!!!!!!!!!!! Author: john122hum Post Posted: Thu Aug 12, 2010 9:47 pm

so i took it all apart and re adjusted them again. I know i did it exactly as per instructions but it makes a god awful noise know. Im not sure what to do at this point. I let it idle for abt 10 mins. The noise is louder than the exhaust and is def a problem. Any advice?

#9:  Re: HELP ME PLEASE!!!!!!!!!!! Author: 1986 XV700 Post Posted: Thu Aug 12, 2010 9:57 pm

john122hum wrote (View Post): thanks for the help terrip. it does have after market exhaust ill try the sea foam. so another question. when installing the valve covers i have stripped one of the screw holes. it wont get tight it barely snugs up. how do i fix this? if it doesn't leak should i even worry about i?
You can put in a Heli-Coil Kit to repair the damaged threads. I want say that its the best or only way to fix it but it would be my preference. The kit I referenced doesn't come with a drill bit and I THINK that's the right bolt size you need to make the repair.

john122hum wrote (View Post):
yeah it was cold have not riden it in a few days. turned the crank to the T mark for the the rear cylinder and the I mark for the front cylinder.

This is just an FYI tid-bit. The only marks that are important when adjusting the valves are the timing marks on the cam gears. Turn theengine , over, till the dot on the cam gear, lines up with the divot on the inside of the cylinder head, not to the left or right, but right on the mark. When these are lined up the valves in that head are closed and you can adjust those valves, then go to the other head and repeat.

#10:   Author: grazingazer Post Posted: Thu Aug 12, 2010 10:12 pm

what scott says is true...there are the "T" mark and the "I" mark on the crank which indicate the piston tdc position but they do it on the compression stroke and the exhaust stroke...the compression stroke is where you need to be to adjust the valves...it is indicated by the mark on the cam gear lining up with the mark on the head as previously stated

#11:  Re: HELP ME PLEASE!!!!!!!!!!! Author: anaman51 Post Posted: Fri Aug 13, 2010 5:33 pm

One other thing that can cause backfiring out the exhaust is leaks at the headers and the joints in the exhaust pipes. You didn't mention what kind of aftermarket pipes they are; some require rejetting, while others just work out of the box. If they're Macs, they should be working without new jets.

Go through the valve adjustment process one more time, making certain that you're where you're supposed to be in terms of aligning the marks on the flywheel. You might be doing it 180 degrees out, causing the clatter. Also, be very specific when you use the feeler gauge. It must slip between the two points with only a slight drag. Check it like this: On the exhaust valves after you've adjusted them, try fitting an .007 into the same space. If the .007 fits, it's too loose.

One more question: You didn't happen to change the oil filter at the same time, did you?

Dan

#12:  Re: HELP ME PLEASE!!!!!!!!!!! Author: john122hum Post Posted: Sat Aug 14, 2010 11:48 am

Im not sure what brand the after market exhaust is. They were on the bike when I got it and they appear to have some age on them. I did the valve adjustment per the Clymer Manual three times and same result every time. How is it possible to do it 180 degrees out?

I havnt changed the oil filter no.

Ive finaly just resorted to tighting up the adjustment screws, putting it back together trying it and then starting over. Its very time consuming but not sure what else to do.

#13:   Author: club_c Post Posted: Sat Aug 14, 2010 11:59 am

Dont just eyeball the adjustment screws and tighten them up. Sure way to ruin your cams or rockers. You need to solve this right or you'll break expensive stuff and be off the road for too long. Do you think the noisy valves are at the front and rear, or just one end. It is very easy to set there rear valves at the T and then overrotate past the I for the front. You only need to rotate the engine about 270*. If you shot past it and thought, oh well I'll pick it up on the next rotation of 360*, that's your problem. So set the rear valves at the T, and then only rotate 270* to the I and set the fronts.
If you've stripped the hole, I would try a longer bolt, those holes are threaded deeper than the bolt you are using now.

#14:   Author: grazingazer Post Posted: Sat Aug 14, 2010 12:27 pm

how did you solve your issues?

#15:  Re: HELP ME PLEASE!!!!!!!!!!! Author: john122hum Post Posted: Sat Aug 14, 2010 7:31 pm

Sounds as if its coming from the front and the rear to me. Set the pointer to the T , adjust the rear valves then turn it clock wise to the I and adjust the rear valves correct? Thats the way Ive done it and theyve made a god awefullsound every time. Its not a little tapping I mean its VERY LOUD.

Ill try it one more time but I guess im not grasping how tighting them slowly, listening to it and stopping with the deffing clacking stops is going to hurt it.

This whole little project is discouraging. I read alot about how to adjust the valves before I started and I thought it would take a couple hours now its been three days and its still not right. I dont get it

#16:  Re: HELP ME PLEASE!!!!!!!!!!! Author: arnie Post Posted: Sat Aug 14, 2010 8:56 pm

I adjusted mine and had the same problem. I was not on the compression stroke. Redid it and runs great.

#17:  Re: HELP ME PLEASE!!!!!!!!!!! Author: john122hum Post Posted: Sat Aug 14, 2010 9:12 pm

hmm can u explain compression stroke to me? appeartly ive bitten off more than I can chew but i would sure like to fix this with out messing up the bike.

#18:  Re: HELP ME PLEASE!!!!!!!!!!! Author: arnie Post Posted: Sat Aug 14, 2010 9:55 pm

Do you have a Haynes or Clymer manual? It will explain the way to do it. You have to rotate the crank os the lines line up and the valves are closed. If valves are not seated, they will be loose when you adjust them. Do a search on this site for (valve AND adjustment)

#19:  Re: HELP ME PLEASE!!!!!!!!!!! Author: john122hum Post Posted: Sat Aug 14, 2010 10:18 pm

I have both but hadnt read the Haynes manual. The feeler gauge goes between the bottom of the adjustment screw and the top of the valve correct?

I know I must sound like an idot to u expeerenced guy. lol Ill try it again tomorrow and let u all know how it goes. thanks for all the help

#20:  Re: HELP ME PLEASE (solved) Author: john122hum Post Posted: Sun Aug 15, 2010 7:20 pm

Figured it out. I wasnt on the compression stroke. I also used the makes on the cam gear. doh Its running better than ever now. Thanks for all your help. Ive learned a bunch on this little project.
ViragoTechForum.com XV750 HELP ME PLEASE (solved)


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