XS650 flooding on left side

[Supertwin Don]

are you still running a vacuum fuel tap? if you are, check that the diaphragm in the tap is not punctured and dumping fuel into the inlet tract - have just had this problem with a GS650 Suzuki.

[GrayWolf]

My XS 650 floods on left side. Petrol comes out the exhaust. There is no ignition happening on this side as exhaust pipe is cold. Any ideas to solve this?

I have a dual output coil with a pamco. Since the fuel spilling out of left exhaust I have: checked and replaced spark plugs, ht leads, and plug caps. Swopped ht leads on cylinders. Replaced floats and pins, replaced float valve and seat. Timing checked and is spot on. Inlet and outlet valve gaps are set correctly. Main jet and pilot jet are not blocked. Float bowl has no debris or crap in the bottom (I have an inline fuel filter in place).

Cheers

Simon

Petcock diaphragm? (vacuum tap)
and as a suggestion.. dirt/grit or sticking/worn float bowl valve ?

I am assuming the floats etc are set correctly and as a last off the wall idea, have seen a leaking/punctured/porous float before now.

[buggerit]

sounds like one cylinder is not firing at correct time, this may be worth a look.

http://www.hughshandbuilt.blogspot.c...n-install.hmtl

[buggerit]

sounds like one cylinder is not firing at correct time, this may be worth a look.

http://www.hughshandbuilt.blogspot.c...n-install.hmtl

check out may 2012 on blog

[gammaguy]

Fuel tap vacuum port pulling in fuel.

[surfer]

Woudl it be possible to swap the carbs side to side and see if the problem moves to the right cylinder? That would definitely prove whether its fuel or spark.

does the problem happen when the bike is on the side stand? Is the stand on the left side of the bike? could the float height e incorrect or the float sticking down?

Not possible to swop carbs. Carbs are left carb and right carb connected by a T fuel pipe in middle which slots into side of each carb.

Yes, the problem does happen when bike is on side stand, and when it is upright.

[surfer]

champ.





Unless its over fueling/flooding. What does the plug on the left taste like?

Rather delicious

[surfer]

Petcock diaphragm? (vacuum tap)
and as a suggestion.. dirt/grit or sticking/worn float bowl valve ?

I am assuming the floats etc are set correctly and as a last off the wall idea, have seen a leaking/punctured/porous float before now.

I took the float bowl off and turned the fuel tap on. Got petrol flowing out nicely. Then pushed floats up but got a continuous dribble of fuel coming through. I guess float valve was not seating properly.

I took float valve seat out and cleaned recess in carb with wire wool on the end of a cotton bud. I think the last rubber sealing washer on the previous float valve had left a bit of a mess in there and so new float valve was not sealing properly. I also double checked float height as well but seems ok. It is not flooding petrol out of exhaust pipe and pipe is hot around header. I haven't taken bike for a spin yet so don't know for sure. Will update later. I expect I will also have to tune carbs.

Cheers everyone for your suggestions and help.

[surfer]

Well, I took the beast out for a blast and all was great. Until i did about five or six km and then it started spitting on left cylinder. Ended up running on the right pot only.

I think it was fine until it warmed up.

I swopped the ht leads over, works fine on the good cylinder only. I took the spark plug out of the left cylinder and held it against the engine case - no spark. Put a new spark plug in and was fine. I think i have an eke trical problem.

[neels]

Well, I took the beast out for a blast and all was great. Until i did about five or six km and then it started spitting on left cylinder. Ended up running on the right pot only.

I think it was fine until it warmed up.

I swopped the ht leads over, works fine on the good cylinder only. I took the spark plug out of the left cylinder and held it against the engine case - no spark. Put a new spark plug in and was fine. I think i have an eke trical problem.

I had an old kwaka that had similar problems, and an old yamaha, nothing like pulling plug leads at 100k on Tram Rd to figure out if its firing or not. What this has taught me is start with the carbs, when they are sorted look at other things

Sent from my electric telephone

[Motu]

I went round and round in circles with this same problem with my XS1. After 20 min or so the left cyl would cut out. Did all the replacing electrical stuff and couldn't seem to nail it. I think I got a big improvement after sorting out the mechanical advance unit. I had replaced the carbs at an earlier time, with Mikuni slide carbs, and then with Blue Magnums, this problem turned up not long after I went back to the original carbs. I gave the bike to a mate to sort out, he has a huge collection of XS650's and parts - turned out it had 2 different carbs on it. I'd obviously ditched them because they were a problem...refitted them when an electrical problem appeared....and then it was all masked by the carbs again.

The XS1 is quite different to later XS650's, and a lot of parts are unique to it. I'm pretty sure the cutting out on one side was electrical, because if I let it sit for a while, it'd fire up and run well for another 15 minutes. Not a lot of help, it was some years ago and frustrating and confusing at the time. I can't really remember...but I think I found the points sticking on the pivot arm. Too much swapping of parts happened for me to remember exact details.

[GrayWolf]

Well, I took the beast out for a blast and all was great. Until i did about five or six km and then it started spitting on left cylinder. Ended up running on the right pot only.

I think it was fine until it warmed up.

I swopped the ht leads over, works fine on the good cylinder only. I took the spark plug out of the left cylinder and held it against the engine case - no spark. Put a new spark plug in and was fine. I think i have an eke trical problem.

One thing the Xs's were/are prone to is wear on the points 'cam and shaft' they wear out and wobble ( the complete cam and shaft) the electronic ignition models didnt sufferfrom this issue.

[Akzle]

coils tend to fail more when hot

[surfer]

First, many thanks for people's interest in coming up with solutions to help sort out the problem. Hope this write up helps the next person.

An update on XS 650 floods on left side with petrol coming out the exhaust on the flooding (left) side. The exhaust pipe on the flooding (left) side is cold (not surprisingly).

The bike has a dual output coil (means only one coil which does both ht leads) with a pamco (no points). Has a PMA stator and no battery - running a capacitor instead. Velocity stacks are on the carbs and an inline fuel filter is in place. The engine is stock and the carbs are mikuni BS34s.

Initially the bike was stumbling in mid-range and this got worse over a few weeks of riding. So bad that it was firing erratically on one side. I did the simple easy stuff first: Checked the timing and valve clearances, checked to see if valve springs were broken, checked compression and all good. Checked the voltage output and all good. Replaced spark plugs and ht leads, swopped ht leads and spark plugs over to see if it made a difference – it didn’t.

Then I stripped and cleaned out the carbs, they were clean with clean float bowls. Put them back together; still got the stumbling problem when I rode the bike only much worse - firing really erratically on the one side.

Stripped carbs again. I noticed the carb diaphragms were full of tiny pin holes when I held them up to the light – beats me how they worked. Initially I glued them up with rubber cement and put small cloth patches (and we are talking small here) on the bigger tears which worked ok until new diaphragms arrived - didn't make a difference though to the problem. Replaced the diaphragms. Just for good measure I replaced the carb boots as well. Bench set the throttle butterflys - this made no difference either.

I swopped floats, float valves and needle float over from one carb to the other. After which the bike totally flooded on the good (right) side, petrol poured out of exhaust. Ah ha – found it, so I changed all the parts back. Then I checked to see if the floats were working by removing the fuel bowl and pressing the float up. Nope they were not, petrol just poured out. When I changed over the float valve needle and seats the rubber gasket ring tore and left a tiny bit of rubber on the inside of the recess for the float valve needle seat. I cleaned this out thoroughly. I replaced float valves, float needles and seats, and floats just for good measure.

I stripped and cleaned the carbs again (in the end I did this three times). I also changed the oil four times because the petrol ended up in the engine – stinky fuel oil and higher level of engine oil.

Still spat and ran erratically on the bad (left) side with a cold exhaust pipe. A quick double check of the float levels revealed the bad (left) side was out. I measured it and compared it with the manual and with the other carb. Just to make really sure I attached a clear tube to the carb bowl drain and held it against the side of the carb to check the level of petrol in the carb bowl.

It still spat and ran erratically on the bad (left) side. I changed the coil and pamco - no difference. In the end I changed the rectifier/regulator unit. I think this was the real problem all along. When it got warm it started to break down. But all the stuffing around with carbs and replacing bits and pieces masked the underlying problem by creating a new one.

The bike runs sort of ok now, it has a slight mid-range stumble. The plugs are carbon fouled so running rich. I still need to tune the carbs as I only bench set the butterflys. I will experiment by going down to the next size pilot jet to cure the stumble and by tweaking the mixture screws. (I’m not going to bother with fitting a set of Canadian needles). So fingers crossed – all good.

[Motu]

But all the stuffing around with carbs and replacing bits and pieces masked the underlying problem by creating a new one.

Exactly mirrors my XS1 saga. I did have a carb problem, and after several years of playing with carbs picked up an electrical problem, but still had carbs to sort....swapping between carbs and ignition,it was a bit of a headache. Like my time with British bikes in the '70's and 80's, it was a lot of work sorting out decades of abuse and incorrect parts....and then adding to the issue by making my own modifications.