Recommended spark plugs with Tri-spark

Hi all,

I just installed a Tri-spark on my MK III and after going through the setup very carefully, I find that I have less than optimal performance. The machine had always been a reasonably good cold starter - even with the electric start - and on the road it ran reasonably well, with throttle roll-off backfire problem that I have been working on. After installing the Tri-spark, I find a cold start to be difficult and it now has a erratic idle with a sputter/back-pop. Even when warm the idle has some sputtering. The throttle response on the road is excellent with good power through RPM range in all gears.

I read the trouble-shooting guide and noticed that it the following verbiage: "It is recommended that high tension lead suppressor caps be used with this system. Use 5k Ohm caps such as NGK LB05EP." I currently have a set of NGK BP7ES plugs installed and was wondering if this might be the source of my problems. And if a different plug is needed, which ones would be a good choice? Or should I just be investing in a different set of plug leads for the same spark plugs?

Thanks for any advice.

The NGK BP7ES is a good plug but I would go with the BPR7ES to eliminate the posibility of electrical noise.
Unless you are playing with timeing for a special reason, there is no reason to go to a hotter or cooler plug.
Here is another good option, NGK iridium spark plug BPR7EIX.

There was a question as to the correct parameters so I email TriSpark cause the paper wasn't too clear.
Stephen Kelly from Northstar Electronics - Tri-Spark Ignition state 30 degrees BTDC @ 4000rpm.

Hi Tim,
I would guess that something is basically wrong with your set up. I say this because I am running a Trispark ignition on my MK-3 with stock (new) Amal carbs and my bike runs amazingly well. I replaced a Boyer system that was OK but as soon as the Trispark was installed the performance at all speeds and startup at all temps was almost perfect. It idles like I have never heard a British twin idle, again almost perfect.

Carbs? Valves? Something is amiss. I hope you find it. Good luck.

Andy

Matt at Colorado Norton Works recommends the NGK BPR7ES with the Tri-Spark Ignition... I trust his judgement completely.

Good Luck diagnosing your problem.

What is the effect of altitude on setting the timing?

I have asked Matt at CNW to send me a Tri Spark when he get his new order in.

I am at 6000 feet altitude, should I set the timing a couple degrees more advanced than the installation states ?

highdesert said:

What is the effect of altitude on setting the timing?

I have asked Matt at CNW to send me a Tri Spark when he get his new order in.

I am at 6000 feet altitude, should I set the timing a couple degrees more advanced than the installation states ?

Click to expand...

At 6936 I would imagin Matt at COLORADO Norton Works would surely know.
What do you do special to your current setup?

highdesert said:

I am at 6000 feet altitude, should I set the timing a couple degrees more advanced than the installation states ?

Click to expand...

I live at 5000 ft. (minus 10' or so) and I have my static timing set a 28 degrees. Perhaps I should try advancing it a few degrees tomorrow and see the what the effect is. I guess that I could ask that any other high-altitude Tri-Spark users to chime in with their settings. OTOH, since I bought the unit from CNW I could give Matt a call on Monday.

pvisseriii said:

The NGK BP7ES is a good plug but I would go with the BPR7ES to eliminate the possibility of electrical noise.

Click to expand...

I went out and picked up a set of NGK BPR7ES plugs to be installed and checked out tomorrow.

Minor deviation of the thread: to help address the backfire problem that I have been having I had ordered a set of exhaust nuts with extra deep threads from RGM (item number 559). These are needed because I have a set of Viking headers that are in the 750 style (flat faced at the exhaust inlet end) and I wanted to maintain the 850 exhaust rose appearance. That order arrived today and that may help the idle stutter/popping and the pronounced backfire at throttle roll-off previously mentiomed. I have been using 2 exhaust washers in an attempt to provide an effective seal and proper spacing of the pipes, now I can use 1 washer and tighten the nut correctly. If that doesn't help, I'll have to look at the intake end and pull the Amals for examination and general going-over (not a pleasant prospect).

Tim,

As far as Amals go you might want to think about buying a new pair. I found mine online (back in Mass I think?) for around $275 for a brand new set. Then I was able to tear into my old and very well worn set at a relaxed pace and learned alot in the process. My original intent was to toss the Amals and install a Mikuni. I am so glad I changed my mind. Just food for thought.

Andy

Andy,

I actually have another set of Amals temporarily available. My '73 750 is completely disassembled with the engine being refurbished and the tank, side covers, and frame headed for the painter. I had planned on doing a rebuild of the Amals for that bike, so I could either use those as a training tool or swap carbs with the 75. I had thought of getting a Mikuni conversion kit for the 75 this year but the 750 ambushed this seasons toy budget.

Trispark; Mexico City; 7400ft; 31 degrees. Makes a noticeable improvement in performance. I believe the engine would accept more but advancing the timing also advances it for kickstarting and anything beyond the 31 will cause kickbacks when kickstarting. At Mexico City altitude the bike is loses around 12-13HP compared to sea level.

This is one place where a "custom" timing curve would be nice - 0 degrees below say 500 RPM and then somewhere around 35 at 3500 and up. I think the bike would react well to 35 degrees of advance for the alt but starting it at that setting is almost impossible if you want to keep your knees intact.

Mine is set for 28* @ 4000 rpm. That's what Steve told me. Still running steel wire leads and Champion plugs, no resistors.