NC35 out of storage, won't get past 5500RPM

[SimonCNZ]

Hi.

Hoping somebody might be able to point me in the right direction.
Have an RVF which was running pretty well prior to moving and putting it in storage for 2.5 years.
Now trying to resurrect it, and @ 5500RPM power drops way off in second gear with no way it's going to get any higher.
Prior to starting, I drained the old fuel, took out the carbs, opened them and cleaned through the jets and needles (albeit quite briefly with carb cleaner and an air compressor), checked plugs and cleaned them (a little carbon as bike has always run slightly on the rich side).

Bike is running a full exhaust system with 112 jets, HRC CDI, standard air filters, pilot screws @ 1 & 3/4 turns out (1 & 5/8 was too rich), and needles with a .5mm washer.

Idles well, although the front left cylinder exhaust header runs warm while the front right runs hot (can't remember if this was the case before).

Bike was dropped on it's side for a few days due to movers not strapping it down properly in a container - but apart from a tiny bit of cosmetic damage (fairing, tiny dent in fuel tank), I was lucky that it fell on a blanket.

After starting with choke on, and taking choke off, it idles pretty well - quite slow sometimes to drop from approx 3000rpm to 1300rpm. In taking it out, it accelerates fine to 5500rpm then the engine power dies off with no way it's getting past 5500rpm.

Speedo hasn't been messed with - could it be a limp mode of some sort? Feels more like fuel, but the carbs were looking pretty good.
Changed the fuel vacuum tube while I had the carbs out (old one was pretty soft).

Any ideas?

Cheers

[magg]

Hanging idle is usually lean idle mixture. Have you measured the battery voltage when approaching 5500rpm. Does engine rev quick and clean above 5500rpm when in neutral. Dissimilar exhaust header temperature suggest a mixture mismatch at idle.

[magg]

Hanging idle is usually lean idle mixture. Have you measured the battery voltage when approaching 5500rpm. Does engine rev quick and clean above 5500rpm when in neutral. Dissimilar exhaust header temperature suggest a mixture mismatch at idle.

[SimonCNZ]

Thanks Magg. Decided I would take the carbs out again today and thoroughly disassemble and clean them through. Will put back to factory 1 5/8, and make the 12.5mm carb card template (it's too difficult to be 100% accurate with a ruler). In neutral it revs freely above 5.5k. Haven't measured battery. Each plug gets spark, and I cant find any electrical reason why it would go in to any sort of limp mode. I could try a back up non hrc cdi but will investigate the carbs firstly again.

Re: HRC CDI. Does anyone know what this actually changes? I've read that it advances timing. What would be the impact on the carb setup?

Thanks

[magg]

While you have the carbies off I suggest you remove the needle washer. The 5500rpm problem may be an over rich issue caused by the richer needle setting. Any chance you can nurse it through the 5500rpm point to see if it clears up at higher revs.

[SimonCNZ]

So stripped the carbs and gave them a really good clean out. I thought the jets were 112 but they are infact 110. Interestingly enough I found that whoever played with the carbs in Japan had the emulsion tubes round the wrong way (front in back, back in front), so switched those back. Took the pilot screw to factory settings, 1 & 5/8.

Still idles well, and get's past 5500 easily in 1st, slight hesitation in 2nd, and have to push it through in 3rd. Left washer under the needle as that solved my problems years ago. So do you think it's slightly too lean or too rich in the mid-range? Past 7500RPM it flies, so no probs at the top end.

The front left cylinder is still much colder than the others during idle - can touch it vs splashing water on the others to see steam. In the mid to high it heats up well (but still not as hot). Checked that plug after the run and it looks fine (both colour & spark). I'm wondering if that cylinder is struggling hence the 5500 issue...

[magg]

Have you checked the mechanical balance of the carbies, the left front one may need adjustment. You could either remove the washers from the needles or add one to each to see what if any change it made to the 550rpm issue and go from there.

[SimonCNZ]

I'm not sure if the cylinder is related to the 5500RPM issue (I'm thinking it's probably not), but I want to try to isolate that first before changing any jetting. I pulled out the carbs again and triple checked cylinder 2 carb. Needles and jets all fine and clean, float height fine and not sticking (although the condition of the carb is pretty average compared to the others, discolouration etc). I slightly adjusted the balance slightly as you couldn't quite see the small hole at the butterfly like the other 3. The bowl had fuel in it. Checked carb boot and fine. After warming up on idle I couldn't see any fuel on the plug. So i'm thinking the fuel isn't getting to the cylinder. Tried richening, then leaning the mixture with the pilot screw setting while the bike was running, still no warmth on the exhaust manifold. As soon as you blip the throttle, so say above 2500/3000RPM, the manifold heats up (but not as hot as the other 3, you can still touch it). In riding it through mid/high, the manifold heats up fine.

Tested HT lead and ignitor with a multimeter, in spec. Tried different plug, same result. Tested alternator, fine. Tested cables to rectifier, fine. Testing rectifier, not getting any readings on any pins, but need to check this again. Not sure a dead rectifier would just effect cylinder 2.

Stumped. I don't have a compression tester - but thinking a vacuum leak further down somewhere? Or valves?

[Suzuki416]

I'm with Magg - Balance the carbs - its very possible that carb is also running lean. Going to ask the dumb question - Did you leave the bike on the side stand? You may need to ultrasonic the carb if the balance dent fix it.

[SimonCNZ]

It was on a paddock stand for most of the storage time, past 9 months on it's side stand. Image of the carb in question (the discolouration/markings is only in this carb);