[gypsy]

i'm not sure why, but the jbm industries diaphragms i used on my 87 vt1100c both tore after a very short time. i have replaced them with the stock oem slides and diaphragms off my 98 spirit (hich is now under a severe overhaul). i've done a couple or diaphragm replacements and never a problem. any ideas? while i was doing the rubbers i also put in the dynajet jets and needles from the 98, the 87 ran like a banshee. however my mileage dropped to the mid 30' so i took her down again and put 165's and 142's in along with an ignitec cdi. well, not nearly the top end or high rpm power that i had with the dynajets. during the last trial run today, i also changed out the ignitec cdi with the stock box and it did perform a bit better, telling me that ignitec (the non-adjustable model) does not perform as well as the stock. i'm sure their adjustable box would, of course, run as hot as you adjust it to run. i run a k&n and have removed my baffles. originally it had 155's and 142's with one washer (shim). the configuration i now have is the one recommended by the jet companies chart. so i see that if i want to haul azz and don't care about the mpg's to go with dynajets kit. the tapered needles and their larger jets DO make a big difference. i remain bewildered by the failure of BOTH of the jbm rubbers??

 

[Spool]

I don't really have any answers for you. Just wanted to say I was quite leary of the jbm diaphragms this past spring when I replaced mine. I wasn't completely confident in cutting the old ones off and gluing the jbm ones on. So I ponied up for new factory slides/diaphragms. Reading this makes me glad I went this route.

I wonder if you got old stock somehow or maybe if the glue you used had something to do with it?

 

[gypsy]

they looked good, not dried out and i was careful with the glue. and why both of them??

 

[ttexastim]

Thanks for the heads up Gypsy. I used those JBM things last year. I'll keep an eye and see if I have the same results.

 

[balloonot]

That sucks Gypsy. I'm sorry for you buddy. I was gonna get them as a back up. My stockers, the last time I looked were still good. But I think I'm gonna go the OEM route too.

 

[gypsy]

You know, I'm getting so good at this getting to the vt1100 carb thing that it's almost and I do mean almost a walk on the park. Ttexan also has the JB rubbers and his are holding up.., so far. I'm sure I did them right, besides why would both tear? I'll go back to the oems and bite the $$ bullet. It's all part of the sport, eh. Thanks for the thought bal. cheers


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[Leathel]

I thought the 87 was like the 93 in that it had matched carbs, unlike the single pin engines and ran the same main jets for both carbs?

I got my economy back with bigger jets and dropping the adjustable needle, slightly less top end but only near limiter but the rest was still mint, the drop in power was not a place you use as it still pulls very well to 90mph in third and a little more but I have shifted well before then mostly

I went OEM vacuum pistons but they are a little pricey

If I went Ignetec it would have been the adjustable one but I still have OEM but may go that way one day to try it..... but then you will need to tune it to the bike and I dont want to tackle that ATM

 

[gypsy]

I thought the 87 was like the 93 in that it had matched carbs, unlike the single pin engines and ran the same main jets for both carbs?

I got my economy back with bigger jets and dropping the adjustable needle, slightly less top end but only near limiter but the rest was still mint, the drop in power was not a place you use as it still pulls very well to 90mph in third and a little more but I have shifted well before then mostly

I went OEM vacuum pistons but they are a little pricey

If I went Ignetec it would have been the adjustable one but I still have OEM but may go that way one day to try it..... but then you will need to tune it to the bike and I dont want to tackle that ATM

the manual calls for the same jet size front and rear on the 87 i went with 65's main and 145 low speed. i think the dynatek's were actually around 70's. your elevation, i'm assuming is much lower than albuquerque's at a mile high, so you will see a big improvement with less gas consumption using larger jets. i'm 99% that i did the install correct on the diaphragms. i followed the directions to the letter. now ttexan has been running them with no problem so far. however with both of them tearing, well im just not sure. at $20 each they are a real deal. outside of the work getting them in the carbs, its a low cost gamble. the ignitec adjustables are about $160, again not a bad price for such a unique cdi. they are adjusted by computer through a cable provided. i believe you can do it with the bike running? i'd try one but i found a discontinued dynatek for my 98 spirit for $60 last year. i used the ignitec non adjustable on my 87c. anyway.. good luck with your m/c efforts.

 

[Harryc]

As long as we're discussing jets and I have the carbs out of my bike rejetting it with a Stage 1 Dynojet kit let me ask the experts a question. My single pin 1996 ACE VT1100C2 comes with different sized main jets from the factory. The front is 175 (Honda OEM) and the rear is 180 (Honda OEM). The dynojet kit came with (3) pairs of matched jets...165, 170, and 175. The instructions say to put the same sized jets in the front and rear along with the vacuum needle changes. The instructions also say to use the 170 sized main jets from the kit if all you've done is installed an aftermarket exhaust with free flowing baffles and have not changed the air intake. I'd assume that is what I've done by installing Vance & Hines Classic II pipes. So I put 170's in the front and rear. Is that correct? I was very tempted to put a 170 in the front and a 175 in the rear, only because it kind of makes sense. On the other hand I've read not to compare stock jetting to Dyno-Jetting because Dynojet jets are not the same as factory, particularly considering the different vacuum needles they use that work with the main jets. Your thoughts? I did email Dynojet with the same question.

 

[gypsy]

As long as we're discussing jets and I have the carbs out of my bike rejetting it with a Stage 1 Dynojet kit let me ask the experts a question. My single pin 1996 ACE VT1100C2 comes with different sized main jets from the factory. The front is 175 (Honda OEM) and the rear is 180 (Honda OEM). The dynojet kit came with (3) pairs of matched jets...165, 170, and 175. The instructions say to put the same sized jets in the front and rear along with the vacuum needle changes. The instructions also say to use the 170 sized main jets from the kit if all you've done is installed an aftermarket exhaust with free flowing baffles and have not changed the air intake. I'd assume that is what I've done by installing Vance & Hines Classic II pipes. So I put 170's in the front and rear. Is that correct? I was very tempted to put a 170 in the front and a 175 in the rear, only because it kind of makes sense. On the other hand I've read not to compare stock jetting to Dyno-Jetting because Dynojet jets are not the same as factory, particularly considering the different vacuum needles they use that work with the main jets. Your thoughts? I did email Dynojet with the same question.

yes, the dyna's have a different sizing number than stock and they run larger. i suspect the reason for the different sized jets in the front and rear cylinders is due to the very lean settings on the sock machines. i believe that even the split cranks where divided as time went on. the "too lean" isue is one we all seem to have to deal with especially on the 1100"s. i do believe it is one of honda's ways of doing emissions control. however once you bump up the fuel in the air fuel mix, i think you pass that ultra lean spot that creates the need to run different sized jets in the front and rear cylinders. in the end, dyna has been very successful based upon the performance of their kits... go with what they say, we know it works. anyway, i'm not a lab tech, just another shade tree trying to get a few more horse power out my honda... and lovin' it good luck harry... enjoy.

 

[gypsy]

" the ignitec adjustables are about $160,"

that's a hundred bucks off... $270 is more like it. still a good deal. sorry for hitting the wrong key :neutral:

 

[Harryc]

Gypsy it's what I thought too, but that gut feeling was bothering me. Thanks for the confirmation of what Dynojet says. I feel better about putting her back together now.

 

[Harryc]

As a follow-up - I received this Email reply from Dynojet.

During our testing and development of the jet kit we found that the bike runs smoother with the same size jets in both cylinders. With the exhaust that you installed, use the DJ170 main jets.

Let me know if I can be of any further assistance.

Thank You!

Michael Cory
Research & Development
Phone: 800-992-4993 Ext 1123
[email protected]
Dynojet Research Inc., Dynojet Dynamometers, Powersports Dynamometers, ATV Dynamometers, Fuel Tuning, Powercommander, Powervision, Jetkits, Widebandcommander, CMD, CMDM, High Performance Dynamometers, Automotive Dynos, Powersports Dynos

 

[Leathel]

some of the single pin engines run different vacuum pistons and springs for each carb...but not all single pin engines.... ????
It wont hurt to try the same jets per pot

FAQ Mikuni vs keihin vs dynojet

that is a chart to compare the Keihin to Dyno sizes

 

[Harryc]

some of the single pin engines run different vacuum pistons and springs for each carb...but not all single pin engines.... ????
It wont hurt to try the same jets per pot

FAQ Mikuni vs keihin vs dynojet

that is a chart to compare the Keihin to Dyno sizes

Thanks for the chart. It says a Dynojet 170 is comparable to a Keihin 190....wow. 10-4 on the different vacuum slides and springs. I learned the hard way on an ACE 1100 they are different front to back, and have since only worked on one carb at a time. . If anyone ever runs into 'that' issue you can search for a thread here that has pictures of where the slides and springs go for an ACE 1100. It took a member here who was nice enough to disassemble the carbs on his perfectly working bike to straighten out that mess for me. Every time I think about that event it endears this site to me. I mean ... who does that?

 

[Leathel]

Thanks for the chart. It says a Dynojet 170 is comparable to a Keihin 190....wow. 10-4 on the different vacuum slides and springs. I learned the hard way on an ACE 1100 they are different front to back, and have since only worked on one carb at a time. . If anyone ever runs into 'that' issue you can search for a thread here that has pictures of where the slides and springs go for an ACE 1100. It took a member here who was nice enough to disassemble the carbs on his perfectly working bike to straighten out that mess for me. Every time I think about that event it endears this site to me. I mean ... who does that?

I went as large as 200 with the needle on the 2nd clip down for a bit but I needed better economy and I think I have 190's in (or was it 185) and the same needle height and got better miles without loosing to much power

178 with the 3rd clip was a little flat but 4th went well.... just drank the fuel.

 

[Harryc]

I'll have to keep an eye on the fuel. Dynojet recommended the 170's (Keihin 190's) and the 4th clip down. 2nd clip is gone ... had to trim it off to fit in the needle holder.

 

[John Hopkins]

i'm not sure why, but the jbm industries diaphragms i used on my 87 vt1100c both tore after a very short time. i remain bewildered by the failure of BOTH of the jbm rubbers??

One of the problems with diaphragms is getting the rubber bead to locate and stay in the groove while fitting the spring and cover, if you still have the old diaphragms look at where the splits are, could they have been caused by being trapped?

When I refit diaphragms I use a very small smear of silicon sealant in the groove just enough to hold the diaphragm in place while I fit the spring and cover.. I don't use much because that stuff can cause a blockage if it gets where it shouldn't..

I don't think JBM would be able to sell the product if it was really bad..

John.

 

[gypsy]

One of the problems with diaphragms is getting the rubber bead to locate and stay in the groove while fitting the spring and cover, if you still have the old diaphragms look at where the splits are, could they have been caused by being trapped?

When I refit diaphragms I use a very small smear of silicon sealant in the groove just enough to hold the diaphragm in place while I fit the spring and cover.. I don't use much because that stuff can cause a blockage if it gets where it shouldn't..

I don't think JBM would be able to sell the product if it was really bad..

John.

thanks john, i too have a problem thinking jbm's product would not be worthy. however i have done a few diaphragms along the way without any problems. i am cautious with the recess. however, poop does occur. i may have missed something on one but two?? they did tear quickly after the installation. with your heads up i will look again more closely and attempt to remove the super glued rings and rubbers and perhaps try them again... $40 beats $200 every time. besides i'm getting pretty good at carb reoval on the 1100 after more than a few runs at it. thanks for your insight. i want the jbm's to work not just for me me but we all can find ourselves up against the honda $$ machine especially concerning these diaphragms. cheers