Phye07 Posted January 31, 2021 Share Posted January 31, 2021 Wanting to get some other heads thinking on this. I know it's an air/fuel issue, I'm just wondering if it's a nice and easy fix? I've just out my throttle body back on and buttoned up the bike after replacing the thermostat and throttle body hose clamps. When slowly bringing the throttle in the bike revs up consistently. But, when grabbing a handle full of throttle the bike hesitates. I.e. has a momentary lose of spark/fire, then it "catches up" and the mix fuel/air fires and revs again consistently. Essentially, pulling hard on the throttle the bike doesn't fire for a second then resumes working just fine. I understand it could be air/fuel out of sync, it could be not enough fuel getting through fast enough, low power in battery, spark not firing, throttle position sensor. I just want to narrow the search before trouble shooting. Any ideas? that save me time, i.e. not wanting to have to full everything off the bike again, (out of laziness). Link to comment Share on other sites More sharing options...
Member Contributer Grum Posted January 31, 2021 Member Contributer Share Posted January 31, 2021 Did this Only happen After replacing the thermostat and refitting the throttle bodies? - Are you sure your TB clamps are tight and sealing properly? - Are all vacuum hoses refitted correctly with no cracks or leaks? - Any chance of condensation in your fuel tank? - Possibly a fuel filter issue or even spark plugs, how old would the plugs be? Link to comment Share on other sites More sharing options...
Phye07 Posted January 31, 2021 Author Share Posted January 31, 2021 Hey Grum, Thanks for the response man. Firstly, yes it started after fitting the thermostat and putting it all back together. Clamps on the throttle body are tight within the tolerances. All Vacuum hoses are fitted and I fixed one that was split,( replaced with a fresh one). No condensation in the tank, luckily. Sparks are all good. Only happened after buttoning up the bike after doing the thermo and clamps. My thoughts have been either fuel filter or a restriction in the fuel line possibly? I had the same issue on my 09 Triumph Tiger 1050 and it just went away after a few days, so never ended up investigating the root cause. Never posted on a forum before, but wanted to eliminate causes to save time in pulling it all apart again. 👍 Link to comment Share on other sites More sharing options...
Member Contributer DannoXYZ Posted January 31, 2021 Member Contributer Share Posted January 31, 2021 vacuum leak - this leak causes more air to flow into engine than normal when you crack open throttle quickly. It bypasses normal intake tract and filter. i guarantee if you take it all apart and put back together at 1/2 speed and verify each step 3x, it will be gone. Link to comment Share on other sites More sharing options...
Phye07 Posted January 31, 2021 Author Share Posted January 31, 2021 Hey DannoXYZ, Thanks for chipping in. I guess I'll just take it all down again. It's not the end of the world. Will posts tomorrow after I've checked it all again. Two or more heads are better than one. Much appreciated for the input DannoXYZ and Grum. 👍 Link to comment Share on other sites More sharing options...
Member Contributer DannoXYZ Posted January 31, 2021 Member Contributer Share Posted January 31, 2021 Rubber is pliable and some times, after many warm-up and cool-down cycles, mismatched joints might wiggle and slide back together. I prefer to do it myself. One thing about rubber manifold tubes inside V is to be careful of procedure. Use same process every time so you can control it. I prefer to: - warm up rubber tubes with heat-gun or boil before installing - install on heads first, make sure orientation is correct, tighten clamps to spec. This is important step because without clamps tight, installing throttle-bodies can actually push the tubes further onto heads and cause a leak. - install throttle-bodies rear 1st or front 1st, fully seated - rock throttle-bodies and seat other bank. might help to have a little rubber-grease on 2nd set of runners. Sometimes, the rubber lips can get folded over and cause leaks - tighten clamps - inspect everything carefully before proceeding Note, this is process that works for me. Others developed other ways that also works. Important thing is to verify everything's seated and sealed before moving on. Link to comment Share on other sites More sharing options...
Member Contributer Grum Posted February 1, 2021 Member Contributer Share Posted February 1, 2021 Are you sure you haven't left the vacuum hose off the Secondary Air Intake Diaphragm (Flapper Valve) on top of the air box, it's an easy thing to forget? Link to comment Share on other sites More sharing options...
Member Contributer Marooncobra Posted February 1, 2021 Member Contributer Share Posted February 1, 2021 Phye07 I had this happen when I last did a throttle body synch. Forgot to reconnect the vacuum hose to the MAP sensor. As well as the poor throttle response I also got a blinking F1 light. As DanoXYZ stated, remove and start again checking hoses are connected. You might even find the issue straight away so you don’t have to strip it all out. Link to comment Share on other sites More sharing options...
Phye07 Posted February 2, 2021 Author Share Posted February 2, 2021 Hey guys, DannoXYZ , you nailed it. I went back and rechecked everything again and again. It took a bit of playing around but eventually after tightening the rubber boots tighter than the spec, the air/fuel returned to normal. Thankyou all for your input. I appreciate everyone's time to give some advice. There is hope for humanity yet. Link to comment Share on other sites More sharing options...
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