Hello folks,

I have been a lurker for a while and used this site as a great resource. I am an amateur bike builder from Aberdeen, Scotland and have been building a 1989 Yamaha TT600. It had headgasket issues so after a few attempts getting it sorted and not having any time to work on my actual project bike, I ended up turning the TT600 into my project. I took it to the bike shed show in london earlier this year:





The bike has a lot of goodies on it (partly due to it being accepted to the bike show and going to be shown in front of thousands of people).

I have been trying to tune the bike to the carburettor velocity stacks I had 3D printed. I know that these bikes run a lot better with the airbox but that option has since sailed.


The bike has been tuned with a 6 sigma jet kit and colourtune plug to try and dial in some of the settings. I have had the carbs in and out the bike about 8 times today making minor adjustments.

Current symptoms can be seen below in the video. The bike seems to bog down after about 1/4 throttle. I cant tell whether it's too lean or too rich...the colour tune suggests its rich but it doesn't make sense in my mind as the velocity stacks should be sucking in air....



Current settings:
Pilot Jet - 50 (from sigma kit)
Main - 140
secondary man - Stock (can't remember the settings)
Needle height - 4th Clip from pointy end on both
Fuel screw - 2.5 turns out (tuned to colour tune)

I have done quite a bit of trial and errors. so far my list includes:

Checking and confirming float height
Ultrasound bath the carbs and confirming orofice clear
checked choke and diaphragm are OK condition
checked for vacuum leaks on inlets and around the carb
checked valve settings are OK (this helped a bit)
various iterations of float jets and needle heights as well as fuel air mixture.

IF anyone can point me in the direction of where to go next that would me much appreciated.

or if you have any questions about my bike, i am more than happy to speak

Thanks
Struan

Bike looks great. any more pics?

Not sure if it will really help you but the stock needle settings for that model were 3rd clip from top on primary and secondary. Did you start with stock settings and end up at 2nd clip from top to try and lean it out?? In general I have found with free flowing muffler on my XT's, I have gone 4th clip from top to richen it slightly and works well. You say yours is 4th clip from pointy end/ or 2nd clip from top which would make it leaner than stock but I have no idea of the effect of the velocity stack so ???

Where is the airbox/airfilter?

Thanks man, there’s a lot on my website, www.remotorcycled.com. Yeah having slept on it and looking back at the colour tune videos I am wondering whether moving the clip to a leaner setting was the right thing to do. It’s like the velocity stack is fine until the throttle is open to a point then it sucks like crazy. Will try a few other things tonight (got a few other main jet sizes)

never mind

Well turbo somehow I dont think he will be observing any life tips given by an obviously grumpy old fart. The bike may not be everyones cup of tea but I can certainly appreciate what has been achieved here. Looking at his website shows he has given the build a hell of a go and done it all to a very high level. More than what most who ride and work on their own bikes have ever attempted or achieved. Most of what I know when it comes to automotive stuff was gained by a lot of research and just giving it a go and quite often learning the hard way. Exactly what is happening here. I dont understand the anger. Why not just assist?

I wasnt calling anybody names, so no need to give me an old fart designation either even if it can be a positive as you'll see bellow.


If you ever looked at my posts, I always help people putting their bikes right.

If you dont see a problem with people first "building" and then realizing they dont know how to make the bike run, fine. We just have different points of view.
Im just like you, learned everything i know the hard way, BUT also learned so much from watching and listening to true grumpy old fart mechanics how things are done, it was amazing how much they knew. The only way to learn their tricks was sitting next to them and doing exactly as they said, they would get mad if you didnt. You dont do as I say? go home! And life tips were always part of the "lesson".



I am still thankful of having those grumpy, farting, old masters teach me all what they did. Am i one already? I will take it as a badge of honor.

Thanks for the feedback, and I appreciate you looking at my site. I have used this as a project to learn and cannot believe how much I have picked up. I agree entirely on the best way to learn is to get stuck in.

I have no idea what your first post was Turboguzzi. It would be amazing to have a grumpy old fart mechanic to learn things off, if you know of any in Aberdeen then point me in their direction. In the meantime I'll go back to the garage and try to figure out where I'm going wrong, I clearly have some learning to do as I have spent too much time "building" instead of...well I don't really know what your point is.