Carbs out again?

[Leathel]

A we while ago I did a carb clean, Fitted the Pingel tap, fuel shut off and a larger fuel filter (least restrictive I could get) replaced the fuel link pipe O-Rings and the bike was running mint, I had a training day on the local race track with it and it had no problems getting to high revs and sustaining it...... but it did show up a slight flat spot mid range...and to be expected with the UK jets in but there undersized piggies and restrictive foam filter removed, giving it a lean spot... but I did 300 miles like that and it was going great.

 I decided to try lifting the main jet needle by adding an extra washer...... and that is when it started to have its super lack of top end...... It runs fine with little throttle up to about 3K but then when I go to open it up more it just dies.....

So I removed the extra washers to get back to what it was....still has the issue, pulled the vacuum pistons again to make sure all was in corect and all was good. Check fuel flow and it seams fine, remove the Filter & Fuel shut off just in case there is an issue with them and no change with those out and straight pipes fitted.

Plugs look lean.... If this was a single carb I would put money on the main jet being blocked.... but I would not think all six carbs would do it at once so really trying to get my head around it..... looks like carbs out again to make sure.... as its got to be either fuel or spark issue.

 The plugs are near new .... and Look OK, Its not likely to have all 3 coils fail under load at the same time..... so back to Carbs?

Oh well time to look further in to it ....typing wont fix it 

[Valker]

Sounds like a vent tube is pinched or kinked. When I added a fuel filter, it caused a similar problem. It put a sag in the fuel line which is bad with gravity feed. My 2 guesses.

[Leathel]

Sounds like a vent tube is pinched or kinked. When I added a fuel filter, it caused a similar problem. It put a sag in the fuel line which is bad with gravity feed. My 2 guesses.

Vent pipe disconnected to test and air flowed freely, When I removed the fuel filter and shut of the hose I used was flat and if anything slightly short, had to hold it on when tightening the clamp.... so flow should not be an issue, I just emptied the tank and the flow from the tap was impressive for gravity flow.  (just wanted test how much reserve it has)

[Harryc]

This was a European bike right? I seem to recall something about a foam piece in the airbox that if removed the bikes ran like crap.

[Leathel]

This was a European bike right? I seem to recall something about a foam piece in the airbox that if removed the bikes ran like crap.

The foam has been out since Nov when I got it and I have put over 3K miles since then without an issue.... and from memory the one I read that had an issue re foam was when he put it on with the K&N it ran rich?


 Still looking for ideas before I pull the carbs.... running out of ideas. I will do one more test run after checking the TPS and coil wire plugs (Unlikely but you got to try)

[da prez]

  Go back to where the problem started. Loose the pingle and try the OEM. Any kink in the fuel line could cause the problem. If the OEM leaks vacuum , take the diaphragm out for the test. If the bike was at my place , this is where I would start.

                                                 da prez 

[Leathel]

  Go back to where the problem started. Loose the pingle and try the OEM. Any kink in the fuel line could cause the problem. If the OEM leaks vacuum , take the diaphragm out for the test. If the bike was at my place , this is where I would start.

                                                 da prez 

The first thing I did was a flow test from the tap, The pingel has a very good flow, almost like it is pumped out..... fuel line is the second.... No change removing the valve and filter with a good angle for flow... Time to bite the bullet and remove the carbs.

[Leathel]

Well when checking plugs it pays to check all plugs, I only tried 3 and they were all the same... the other 3 I didn't check are all black and sooty....The LH bank is all running rich...

I guess sheit in the float valves, I will strip the carbs in the morning to check.... then see if I can get new float valves over here ...and may change the jets too.

[indybobm]

I one bank is running rich and the other is not, check to make sure that the enricher valves are working properly with the linkage.

[rhubarbray]

LOL. I understand your reluctance to pull the carbs again. I just completed a carb strip, clean, inspect over the winter, Dan Marc mod, and other maintenance to the bike. Put the carbs in, used the new Digi-Sync, (nice tool by the way!!) and found it did NOT want to run right. Idle adjust was having nearly no effect, idle was hunting up and down, couldn`t figure it out. Took it out for a run to try and clear out whatever was in the bowls. Over 3000rpm it really pulled but was soft at low rpm. Pulled over and I could almost put my bare hand on cyl 1,2,and 5 headers!!

Carbs out again. Must be some dirt in the low speed jets.

Crap.

[The emperor has no clothes]

I one bank is running rich and the other is not, check to make sure that the enricher valves are working properly with the linkage.

+1 with the carbs recently cleaned it seems unusual for all 3 to be clogged.

[John Schmidt]

Here's something I've done in the past when suspecting debris in the bowls or float passages. Get a MityVac in hand, slip a union of some nature between the MityVac hose and the carb drain hose, then pull some good vacuum with it. Once pumped up, open the drain on one carb only. The turbulence created by the vacuum sucking will pull out various amounts and types of debris. Close that drain screw and move to the next carb....do this on each carb but don't forget to close the drain screws. Once all carbs have been sucked empty, start the bike. Any debris recovered will be in the MityVac's catch all container, you'll be surprised what shows up, especially if the carbs haven't been cleaned in a long while.

[Leathel]

I one bank is running rich and the other is not, check to make sure that the enricher valves are working properly with the linkage.

Looked at the adjustment and workings of those before I checked the fuel flow as I felt it was running rich.... but when the plugs didn't show that I started looking at lean..... I just didn't check all the plugs

[Leathel]

I one bank is running rich and the other is not, check to make sure that the enricher valves are working properly with the linkage.

+1 with the carbs recently cleaned it seems unusual for all 3 to be clogged.

I figure there must have been dirt in the fuel rail that side that dislodged, Not all the same richness as No 4 was really wet, even around the intake pipe when I removed it, that is what got me looking at the plugs on that side..... could have been at risk of Hydraulic lock if it didn't have the shutoff valve.... and when I removed that I was manually shutting the tap off

[Leathel]

Here's something I've done in the past when suspecting debris in the bowls or float passages. Get a MityVac in hand, slip a union of some nature between the MityVac hose and the carb drain hose, then pull some good vacuum with it. Once pumped up, open the drain on one carb only. The turbulence created by the vacuum sucking will pull out various amounts and types of debris. Close that drain screw and move to the next carb....do this on each carb but don't forget to close the drain screws. Once all carbs have been sucked empty, start the bike. Any debris recovered will be in the MityVac's catch all container, you'll be surprised what shows up, especially if the carbs haven't been cleaned in a long while.

Carbs were already out....but I must see if I can find one of those..... could save a heap of time in the future

[Roidfingers]

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[Leathel]

No crap seen in the carb but definitely rich so float valves are most likely the cause

They only had 2 float valves in stock.... so I have those underway and ordered more but I needed the bike so slammed it back together.... but now its flooding on 5 cylinders...Aaaahhh this seams like something I have struck before, random rich issue with certain fuel..... but that bike had a fuel pump..... and oversize fuel line so this being gravity I didn't think it could be that

 I did open up the fuel filter further as I thought it was starving of fuel...... now its flooding all but one cylinder (black plugs)..... My increase of fuel line size and Pingel tap is providing to much pressure for the tired float valves... Volume is pressure, increasing the fuel line size and getting the best angle for flow has been too much

I have put a smaller filter in and a section of 8mm hose and its now running great.... When I get all the float valves I may try the larger line again but for now I am all go .... just got to try a shim in the needles again to see if I can get rid of the flat spot .....sometime

[Harryc]

Too much fuel flow and old float needle valves...good one. I'm glad you got it running in the meantime. Like you said, in a pressurized environment like with a fuel pump I'd have expected to see this (5 leaking valves at the same time), but not so much on gravity feed. It's usually just one that goes first.

[Leathel]

Well an early start with a Dawn service for ANZAC day (Australia New Zealand Army Corps) that my Daughter plays at in the RSA pipe band, I had to do a run back home to get the correct drum sticks for her and it was great riding as the sun started to get close to rising

 After the morning service she heads of to another service near by at 9am....then another at 11am but I decided to pop back and lift the needles..... still a large flat spot and seamed a bit rich..... so it was either drop it again or add air.... I chose the later. I removed the baffle in the air box that sends the air to the front of the box then removed the bends of the intake pipes as mentioned in another thread and that almost got rid of the flat spot, pulls well down low, a slight pause in power between 4-4.5K revs then after 5K its off like a rocket

 No problem hitting the rev limiter in 2nd & 3rd being 105mph in 3rd, hit 4th and it just keeps climbing without hesitation .....apart from mine, I feel it will probably limit in 4th too but I had to back it off for safety reasons, not many places around here with spots I would risk going that fast... and that is instant loss of license and impound the bike  


 I will have to wait for the float valves to show and get those in, open the fuel flow again and see if that affects it ....then wait for the next day to get on the race track or drag strip

[Leathel]

The flat spot from 4-4.5K rpm is only there if you open to full throttle .... If you wind it on its goes through the full rev range without a pause .... still need to finish the intake pipes

 I used to think it had loads of top end.... now it has more.... I really need to dyno it to see the next steps as it still has the factory UK 78 jets and I am not sure how it gets going in the top end so well when the US jets are so much bigger, TPS & Mapping???

 Mates Rocket is supposed to be tricked up and have 145HP but he cant pull away??? I guess his bike has almost 100KG extra weight....make that 80Kg difference as I am heavier 

I will run it a while to see what the fuel usage is like

[Ricky-D]

The flat spot from 4-4.5K rpm is only there if you open to full throttle

Under this specific condition of running a whole host of variables are eliminated, and I would think the answer ought to be pretty evident.

Considering that the engine is an air pump, it is my feeling that you are experiencing some kind of inversion (like cavitation) that is temporarily impeding the smooth operation of the engine.

I would think it has to be related to either the air intake of your bike, or the exhaust system of your bike. Or a combination of the two.

If you have modified either of the two systems, air intake or exhaust, I would suggest to look there for the correction of your trouble.

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