Project Resto-mod Mk.II

[paul doran]

What a lovely bike well done

[Rodders5019]

Looks like it came from Sanctuary's work shop

[ADE]

What a beauty likeing it alot
Ade

[Viktor Larsson]

It lives!

https://www.youtube.com/watch?v=0AEo2J4pgqQ

Runs dodgy as hell here though given that its cold and the carbs are straight out of the box. First I suspected the ignition and coils where the cause of the rough idle. Then after consulting my good friend Steve (of LuckySeven Motorcycles) we kind of agreed on the carbs and / or inlet rubbers being the culprit of the rough idle and the backfiring.

Once I managed to get the engine warm I started to re-tighten some stuff, inlet rubbers were a bit loose so once I re-tightened those most of the backfire was gone. Then I realized I had plugged the vent from the engine cases causing lots of pressure to build up in the engine (bad) so once I removed that the backfire was gone.

On the plus side, I managed to check the engine for leaks by plugging that up and I'm happy to say that there were no leaks at all!


Work with fine-tuning the carbs continues tomorrow then I got to bleed the brakes and wire up the tacho to the ignition so I can see the revs.

[ollie]

nice one viktor

[Viktor Larsson]

It's finished!



Some work left to do on the carbs but it rides and runs and that's good enough for me. Now to get it ready for MOT.

[Jappen]

NICE

[ADE]

Well said Nice very nice.That`s the dog`s dangler`s
Ade

[Viktor Larsson]

Thanks guys.

Small update on the bike: Carbs are tuned well enough for now but I have a problem with back firing and a weak spark on #4. Ordered new coils, wires and caps so I'll be swapping that out as soon as possible and removing the stock coils + resistor which should eliminate the problem.

Need to fit some resistors for the indicators as well as install the brake light switches next so it's ready for MOT.

[Viktor Larsson]

Guys I need some assistance.

Everything is sorted on the bike now but I still have an issue with backfiring on cylinder #4. #4 was also producing a weaker spark.

At first, I thought it was a faulty coil or the resistor that is stock on the Mk.II or a faulty coil wire so I ordered new coils, wires and caps.

Today I fitted the new stuff to the bike and it starts and runs better on idle but the problem with the backfiring on #4 remains.

What is strange is that it only occurs when I open up the throttle and start bringing the revs up in the 2000-2500 RPM area that it starts to backfire. If I back off the throttle it goes back to a perfectly smooth idle.

So the next logical thing to check would be the carbs. I removed them from the bike and thoroughly inspected the carb for #4, removed all the jets and needles and gave it a good checkup and made sure everything was clean and unclogged of any particles with some compressed air. Refitted everything to the bike and started it up again.

Same problem remains.

Perfect idle, answers well on throttle blips, revs go down quickly, etc. Everything indicating that I've tuned the carbs more or less perfectly but still this issue.

The only other points of error I can suspect are:

Poor grounding for the main harness somehow.
Faulty pickup on the crank.
Faulty ignition unit.
Leaking inlet rubber

An ignition issue should translate to both cylinder #1 and #4 since they share the same coil but despite this it is only on #4 that I have an issue so that leads me to believe it is an issue with the inlet rubber at this point.

So what would my best bet be? Take an even better look at the carbs and make sure they are absolutely spotless inside and then make sure the inlet rubber is good (despite them being more or less brand new).


Any advice would be most appreciated.

[Pigford]

Viktor - you state:


"What is strange is that it only occurs when I open up the throttle and start bringing the revs up in the 2000-2500 RPM area that it starts to backfire. If I back off the throttle it goes back to a perfectly smooth idle."
Is this on the road - or with bike stationary ?

Remember, it;s throttle position which is important - not revs, when checking out carb settings! Sounds like part open throttle = pilot jet / slide action.

Hows the fuel/float level for #4 ?

Double check plugs - even if new

[ADE]

I would agree sounds like fuel.I had a problem fine when running normal give it some gas and it popped and banged.It may be your chucking too much fuel
into 4 causing the problem.Spray some carb cleaner through every jet and airway.Hope you get it sorted
Ade

[Viktor Larsson]

Viktor - you state:


"What is strange is that it only occurs when I open up the throttle and start bringing the revs up in the 2000-2500 RPM area that it starts to backfire. If I back off the throttle it goes back to a perfectly smooth idle."
Is this on the road - or with bike stationary ?

Remember, it;s throttle position which is important - not revs, when checking out carb settings! Sounds like part open throttle = pilot jet / slide action.

Hows the fuel/float level for #4 ?

Double check plugs - even if new

On the first question: Both.

I get the same backfiring issue regardless if I'm trying to ride it on the road (because riding below 2500 RPM is quite difficult) or standing with it outside the garage and blipping the throttle a bit.

And you're correct about throttle position. Around 1/8 to 1/6 open throttle and above produces the backfiring issue. The carbs are brand new Keihin CR Specials straight out of the box so that is what has me a bit stumped.

Good going by the amount of fuel that I drained from the float bowl when I removed them. Haven't checked the specific float level between each carb though (again, these are new from the factory) but I'd assume they are the same or about the same.

I'll double check everything tomorrow.

[Al]

Bought new RS flatslides at the start of this season. First thing i did was take them apart.
All float levels different, accelerator pump not correctly adjusted, and a sizable piece of brass swarf in one of the pilot air jets which i could only see with a magnifying glass.
A few small other issues but far from fit and forget.
It still 'eight strokes' until it has done a half or a full lap but after that is perfect with no detectable issues.
Is the same the following day from cold, again until its done half a lap of full right glove. Warming it up in the paddock wont do it for me.

AL

[Viktor Larsson]

Off to try and get the carbs sorted now. I'll let you know later tonight how it worked out.