Opened up the engine, looky what I found

tz375 · Post by **tz375** » Tue Apr 07, 2009 2:25 pm

Jason,

That's the right way to do it, and coincidentally the way I do it

That tall thin cylinder is probably a burette and they are getting to be expensive.

Plugs: Fine wire non resistor every time. If possible Iridium plugs.

Post by **oldjapanesebikes** » Tue Apr 07, 2009 11:28 pm

tz375 wrote:Jason,

Plugs: Fine wire non resistor every time. If possible Iridium plugs.

Thanks - I've always used non-resistive plugs (with resistor caps) , and I almost always use NGK plugs (B8ES or B7ES). I was under the impression though that pretty much all the new plugs were resistor plugs - not true ? For example, the R in the the NGK part number for their iridium plug for the GT550, BR8EIX indicates that it is a resistor plug (uses a 5K internal resistor).

tz375 · Post by **tz375** » Wed Apr 08, 2009 10:17 am

Ian, correct, iridium plugs all appear to be resistor types (Denso and NGK), but they also have extremely narrow tips so they will fire at lower voltages.

There's quite a range of plugs out there today from stock B8ES types with 2.5mm tips, to B8EV with 1.0mm gold palladium to B8EVX with 0.8mm platinum tips through to BR8EIX iridium tips.

Peopel claim that iridium plugs actually make more power, but I have not read any articles to support the claims yet.

Almost any bike will benefit form a change to fine wire plugs, but if iridium is too rich for your blood, look at the platinum tipped VX plugs or EGVs for more complete combustion.

H2RICK · Post by **H2RICK** » Wed Apr 08, 2009 11:50 am

To continue the thread-jacking:
I am NOT a big fan of resistor plugs.....in machines that were not intended to have them originally. Now there might be some electrical engineers that will tell you that they are wonderful things to have in older bikes that were not equipped with them originally (and I have seen learned articles on this very point over the years) but I remain unconvinced. Why add more resistance to a system that, even when new, had barely acceptable plug tip voltages in the first place ?? This point is especially important nowadays, what with the crap the refiners are selling us as "gasoline".
My .02 worth....

tz375 · Post by **tz375** » Wed Apr 08, 2009 12:19 pm

Rick, with conventional wide tip plugs I would agree with you. And Non- resistor plugs are still available in some of the other fine wire types including VX types but they are being phased out.

I suspect that is because modern vehicles have complex electronics that do not take well to RF noise.

One advantage of a fine wire plug like the iridiums is that they fire at much lower voltages and fire more consistantly.

If you are running a bike with stock ignition and it's still struggles to fire an iridium plug, try witching to a non- resistor plug cap.

Anecdotal evidence to date seems to suggest that Iridium plugs fire old bikes much better than any other plug and do so for tens of thousands of miles.

Post by **oldjapanesebikes** » Wed Apr 08, 2009 5:49 pm

tz375 wrote:Almost any bike will benefit form a change to fine wire plugs, but if iridium is too rich for your blood, look at the platinum tipped VX plugs or EGVs for more complete combustion.

Thanks - I'll check it out. One of the reasons I'm curious is that it makes sense to me that when retro-fitting electronic ignitions to these bikes, you'd want to change to resistor plugs for all the same reasons they are used in new machines. The limitation as Rick points out is that you don't want to impact what little spark the coils are able to produce so if the fine wire plugs give a fat spark at a lower voltage, then that sounds like a win-win.

jaybob · Post by **jaybob** » Thu Apr 09, 2009 3:07 pm

Did someone say Iridium plugs.........

Also got the upsize jets used for 1.98ea. from the local mom and pop cycle shop

They only had 35s for the pilots. i am not sure I am going to use them I may look for some smaller ones.

3 each of 120, 122.5, and 125 to try out in the mains.

Triplerocky · Post by **Triplerocky** » Thu Apr 09, 2009 3:37 pm

when I bought my Iridium plugs, I lit a second mortgage on my home... by the way, since they sell them in pack of 4, every 3 packs you get an extra complete set for a triple. So, how many time do you need to wear out 4 plug set made of that exotic metal?

jaybob · Post by **jaybob** » Thu Apr 09, 2009 4:41 pm

I guess it would depend on how many triplesyou have!!

GT Tim · Post by **GT Tim** » Thu Apr 09, 2009 4:55 pm

Just a question...playing devils' advocate here.

Statement sets up the question. I have owned a few Yamaha 2 strokes...fouled lots of plugs. Especially on the GT80 and the DT125. Used the old gold palladium plugs on them too. Those '70s Yamahas had really weak ignitions, especially the previously mentioned, and my RD350 doesn't take any prizes either.

I have owed alot of Suzuki 2 strokes, from TS185's to GT750's. GT250, T500s, GT550s all and now a RV125.

I have NEVER fouled a spark plug on a Suzuki...never. None.

Am I living in some kind of charmed spark plug Nirvana?

Or are anything else besides standard non resistor B7ES (and like) spark plugs in stock Suzuki bikes really unnecessary?

From this perspective, I see no reason to spend that kind on money on something that doesn't need changed.

If I am missing something, please show me.

tz375 · Post by **tz375** » Thu Apr 09, 2009 5:36 pm

The answer Tim is that if they work for you, don't change.

purely anecdotally, some of the guys have had starting problems with triples or missfires and iridium plugs allowed them to start easily and fire cleanly. In theory they will improve gas mileage and power, but I don't think most f us would notice that.

Post by **oldjapanesebikes** » Thu Apr 09, 2009 8:23 pm

GT Tim wrote: I have NEVER fouled a spark plug on a Suzuki...never. None.

Am I living in some kind of charmed spark plug Nirvana?

I'd say maybe you've just had better luck than some folks - I have had plugs foul on my GT750's, but admittedly almost only ever in the spring. After sitting over the 8 months of winter we get up here, they smoke like hell for a while when first starting them up, and usually for the first short while on the road. I normally put in an old set of plugs for that first starting, and then once the engine is cleared out, I change over to a set of 'run' plugs for the rest of the season.

I've always used B8ES plugs, but as offered previously, my interest in resistive plugs was for the case of retro-fitted electronic ignitions and some accessories - a GPS for example.

tz375 · Post by **tz375** » Thu Apr 09, 2009 10:04 pm

Sorry Ian,

You can't fit modern electronic components to a GT750. The electrical system is is to JIS standards and the volts are all different size to US volts. I heard that the pre 74's use no standard amps as well, but that may be a rumor.

Seriously though, the only issue I heard on a GT was potentially that it's easy to take more than the generator gives. I never sat down to work out all the different current draws, but I'd expect it to be able to manage to small amount of power a GPS consumes.

The generator is rated at 280 watts compared to modern bikes which tend to be around 400.

BTW, anyone heard how the GT550 was after the ccing etc?

jaybob · Post by **jaybob** » Fri Apr 10, 2009 8:24 am

I'm working on a new compression guage right now as the fitting on the one I had was damaged.

I did get the needle bearings installed in the swingarm last night. That seems like it will work out OK.

Results to follow...

Coyote · Post by **Coyote** » Fri Apr 10, 2009 8:33 am

In my somewhat feeble opinion, your jets are waaaaaay of the mark and your 550 will probably run like crap. My 550 has chambers and pods - no head skim. I am running 3 over mains (105's) across the board. When you switch to chambers (individual exhausts) all your main jets should be the same.
I started with stock pilots but had some off idle issues. I stepped up to 2 over pilots but that caused other problems like setting a good steady idle and it was blubbery fat. I dropped back to one over pilots (27.5's) and this turned out to be the ticket.
I should note that my slide needles are all the way up in the last notch. I have not done a WOT plug chop yet as my fresh top end only has 260 miles on it. I'm waiting for the 500 mark. I have wound it up to 6,500 and it's pulling like a freight train at that point so I can't be far off. I suspect if anything, she is still a little fat but I won't know for sure till the plug chop comes. If it proves the be a little fat, I should be able to correct it by dropping the needles a notch or two.
So my only mods are a full 1mm oversize top end, chambers and pods. I doubt that the head skim will make that much difference. You might have to look for a good grade of non ethanol fuel to support the added compression.
50 cents a jet is a good price --- unless they turn out to be Keysters, in which you would have been better off buying a couple of beers.
My independent bike shop gets genuine Mikuni jets from dealer only Tucker-Rocky. $9.00 for a packet of 4.