Moto Grand Prix
Main Motorcycle: 1973 Triumph TR7RV
Join Date: Oct 2013
Location: Pleasant Hill, CA USA
Other Motorcycle: 1964 Triumph Mountain Cub
Hi tiger78, Interesting.... Tigers are very good starting bikes. I feel a little easier than Bonnies. However, properly tuned with a good carb & battery all these bikes are good starters. Generally the first kick.
I understand Ohio can be much colder than where I live. I've started my bike at 22f a few times. Always first kick. Many times in upper 20s to lower 30s. Never fails. Lots of times from 40s-60 in garage all winter. I ride all year, did a ride in mild snow last winter.
My feeling is your bike is out of tune. Or.... it's worn out. My carb finally wore out & caused dying at idle & just above idle. Still started well though.
On club rides a few guys have Mikuni on Bonnies or Nortons. I don't see them starting any better. When smoking hot it seems they start worse. Sometimes much worse. At least with Amal concentric you can tickle it hot & give full throttle. It starts first kick then.
Amal Premier Tiger 750 carbs are not so easy to get with slides, jets, banjo, top you want. I emailed Amal direct. Email Phil & tell him what you want. You'll pay by pay pal. Will arrive in 1.5-2weeks. Even if on back order, he can assemble one just for you. Aprox $200 US with shipping. Depending on dollar/Pound values.
They built to my specs. I wanted #3 slide for California fuel. Also make sure you get .019 idle jet. NOT .017 like the original had!! The new Premier is different internally & needs .019. Amal now makes a .1065 needle jet. Slightly larger than normal. I'd recommend that. Needle clip on bottom groove. I'm using 280 main jet & it's working quite well for me. For Ohio fuel I'd probably stay with 3.5 slide. What do you have now & how does it run 25-40 mph?
Always run highest octane fuel they sell even if it contains ethanol.
My bike starts & runs so good I can't believe it after installing new Premier. I made sure all else was perfect before getting new carb.
I think you will find well tuned your Tiger 750 will run with a Bonnie 650 no problem & also run with T140 no problem.
I reworked my AAU to change advance curve. The electronic ignition come with a very desirable advance curve.
Your original points AAU is full advance at 2000rpm. Boyer I know from testing in real life gets full advance 3500 rpm in a liner fashion as rpm increases. That substantially reduces ping. I've not personally tested Pazon, but I have friends that use them & find the advance curve is similar. So either will work very good. I'd probably get the one that is the least sensitive to low voltage.
One thing is points will start & run with a low or dead battery. Points allows bike to at least run even if not properly with a faulty charging system.
It is stupid to not have a perfect charging system & battery. It just makes the bike start & work properly. Electronic ignition is very voltage sensitive. You MUST!! have a perfect charging system & battery with electronic ignition.
I wonder if some of your current woes could possibly be related to low voltage?
What is the float level on your current concentric? If... this is the original carb the level is not .080" below gasket surface, but level with surface or just above with float horizontal. The true way to check is the liquid level on bowl. If want I can repost the Amal float level sheet. You must use a stayup float & viton tip alloy needle. Remember slide/bore wear cannot be overcome. Don't sleeve. Get new Premier.
All the rest of motor, valve adjustment, point gap, clean points, ignition timing, compression must be checked & made good.
So have lots to think about. I don't know if you've already gone over all these other items. If not I'm afraid the Mikuni is possibly going to be no better. I stand by the Amal Premier. Properly installed they start & run really, really well.
Last edited by TR7RVMan; 10-23-2019 at 02:24 AM.
Reason: changed sentence