Random Motorcycle Stuff I Worked on This Weekend

"PyramidHat" (pyramidhat)
01/18/2015 at 22:33 • Filed to: Two Weeks Good, Two Wheels Fucking Awesome

Nothing major...not bitching or needing an answer, just blathering as I am apt to do...

So the [Triumph] Bonneville had developed a mid-RPM miss late last summer, from just above idle to about 3500 RPM, but ran smooth above that. It was also stumbling a little in light-to-light traffic, which was irritating. So, the first thing I went after was cleaning the carbs; didn't find much, but it was a good exercise, anyway. Put it all back together: Nothing. Replaced the plugs, checked the wires (4800 ohms, which is fine for these) and put in a new, hotter coil. Same thing. Checked and adjusted the valves (which is a pain in the balls as I have to pull the cams out and swap shims). Same same. OK, maybe change the air filter? New high-flow K&N - nada. Well, shit since I'm in there might as well remove the baffle and help it breathe better (a popular mod for Bonneville's is to completely pull the air box and install pod filters - I'm not entirely sure I feel like doing that; a mid point mod is to pull the baffle out, which was only installed to reduce intake noise). Same same. I did some reading and learned that even in my previous, non-slightly modified configuration, I needed a larger pilot jet and an additional 1/2 turn on the air/fuel mixture. With work/holidays/relationship, this sat for a few months, and I finally got a free day today. So I upped the pilots one size and got another turn on there...now, the miss is still sort of there, but it's significantly reduced, I think. Didn't get to take it out as I was out of time, but look forward to doing so next weekend...

Maybe the next bike should have fuel injection...

DISCUSSION (12)

bob and john > PyramidHat
01/18/2015 at 22:36

Fi is great. my SV always starts up and runs juuust fine no matter the weather conditons :P

PyramidHat > bob and john
01/18/2015 at 22:41

Now I have heard that some bikes have weird fueling issues, though (flat spots, etc..). Is that just a growing pain for a new bike model (in your experience) or sort of nature of the beast.

But you're right: It's nice that carbs are simple, but it's nice not having a cold-blooded bike. First, I thought it was just the pre-FI Bonneville's, but a guy at work has an older Ducati Monster and he complains about the same thing. The PO told him: I've had this thing tuned and worked on and you just have to accept that it's a cold-blooded bike...

bob and john > PyramidHat
01/18/2015 at 22:42

its just a growing pain. flat spot and what not can ALWAYS be tuned out on an FI bike.

nlzmo400r > PyramidHat
01/18/2015 at 23:15

I can tell you from experience, if you've checked and verified the things you have (carburetors can never be too clean), you can be nearly assured the igniter box is going out. I've diagnosed and remedied this issue many times. The OE replacement is expensive, so people typically choose the cheaper adjustable Procomm unit. I can't say I love these as they fail often as well, but at $300, they're a damn sight cheaper than the OE one.

Regarding the airbox, don't bother removing it, it isn't a restriction. I've dynoed dozens of 790/865 Bonnies and the airbox isn't a restriction at all until you're working with 41mm carbs and reaching for 90-100whp. Unless you just particularly like the look/sound of deleting the airbox, it's no performance advantage.

Lastly, when you get REALLY good, you'll be able to swap valve shims without removing the camshafts; that is unless you go the shim-under-bucket route. Hope this helps, best of luck!

The Compromiser > PyramidHat
01/18/2015 at 23:16

Towards the end of season, I had nothing but issues. Wouldn't warm up, idle right, stall out at every take off. I must've had the plugs out and intake carb opened up and sprayed/cleaned shit 10 times. Assumed it was the cold, low fuel, lousy rider etc. Every time ran like a top (or just better) until i got back with it and it was a mess the next time. Finally hit the forums and found out that I used the wrong gas, was using the "choke" wrong and shouldn't use the throttle when choked.

Now I need to oil/air filter change and replace a cracked rear rotor and possibly demoed pads before the snow leaves.

PyramidHat > nlzmo400r
01/18/2015 at 23:18

Thanks for this! I'll check into the igniter box.

IRT the shims, I'll bite: How does one remove them without removing the cams, as these are shim under bucket? Is there a mod that one can make to remove the bucket and just have the shims in place?

PyramidHat > The Compromiser
01/18/2015 at 23:21

I can see with the gas - when I first bought it, I was putting 91 in and did some reading and learned that I should have been running 89 (can't rightly remember why, now...). How were you using the choke wrong? Admittedly, I have forgotten and left he choke (actually "enrichener" on for several miles until I realized it (I usually keep it on while I'm on surface streets to that the engine keeps running at stops. Once on the freeway - if I remember - I turn it off)

nlzmo400r > PyramidHat
01/18/2015 at 23:29

The Triumph modern classic engines aren't shim under bucket, they're shim OVER bucket. Hence the shim being the first thing exposed underneath the cam lobe and the valve bucket or tappet being underneath that. Nonetheless, after doing so many, I made a small tool to move the camlobe out of the way (after loosening the camshafts) and am able to pluck the shim out without completely removing the cams, thereby saving me the few minutes of getting them timed together again. http://www.dansmc.com/valveclearence… This is a very similar tool to what I made.

Shim under bucket (like the 675 family for instance) uses the camshafts to push directly on the valve buckets which have a shim that contact the valve stem directly. The shims therefore only need to be the diameter of the valve stem (3mm or so on 675s) and reduce weight and force needed to close the valve.

Not sure where you live, but I'm a service manager at a New Orleans Triumph/Ducati dealership ( www.ttrno.com ); if you live nearby or are ever in the area, pass through and I'll be able to show you first hand!

sdwarf36 > PyramidHat
01/18/2015 at 23:31

The keyword here is "developed." If the jetting was the same before as now, it should be running the same.

Clean you jet needles. ( the tubes with the holes in it that the needle goes into.) Get a torch tip cleaner (for cleaning oxy-acetyline torches) Find one the right size for the holes + go thru them all.

Where you describe the stumble, is coming off the idle circuit + going into the needle. As it goes up, it exposes the holes. The lower holes are restricted. You'll never see it-a couple of thousands of hardened crap gas. Its just enough to make your stumble-more throttle you open more holes + richen things up.

Sighed,

someone whos cleaned 100's of bike carbs.

PyramidHat > nlzmo400r
01/18/2015 at 23:35

Oh! Yes - OK, it was messing it up in my head. I forgot that the shims sit in that little spot on top of the bucket - thanks for the clarification. Have you marketed your cam lifting device on TriumphRat.net?

Also, thanks for the invite! I'll remember that the next time I'm down in NO (went there for the first time in 2012...I'm still working off those beignets...)

nlzmo400r > PyramidHat
01/18/2015 at 23:38

Only made the one tool. Just did it so it'd be easier/faster for the guys to get them done during services. Hopefully you'll take me up on the offer. If you ride in, you've got a safe/secure place to store the bike as well.

The Compromiser > PyramidHat
01/18/2015 at 23:44

I was doing the same. Running 94 octane. Turns out the PCM doesn't do variable timing... this negates the effect of high octane and leads to build up.

The choke is an enricher as well and not a real choke. The excess fuel 7t delivered meant it had to be monitored and adjusted as it warmed up. If I touched the throttle it dumped too much fuel and again, build up. I pulled the plugs and could see how fouled the cylendars were ( odd angled of my head and a flashlight through the other plug hole). I Seafoamed the bugger and it wasn't spotless but it was much better. I scrubbed the plugs with a brass brush and they loked good for the end of season. I may replace them anway, I dont know how long they were in and whag abuse they had heaped upon them.

It turns out the 1300 Honda engine is a complete nightmare according to my mechanic, and the internetz if you pay too little attention to it. Or too much I guess...