87 VR --New purchase... Work In Progress

[pvw10121]

Purchased an 87 VR a last week (named it PV1... cause I actually bought two VRs... this one, and an 86 (named PV2)). Normal story with PV1... been sitting a while... has some carb issues.

 

I've pulled the carbs (twice, so far). First time was to fix an overflow issue with carb #2 . Float tab had pulled away from the float needle. Easy fix. Got it started (without pouring fuel out the overflow)... but running poorly. Pulled the carbs a second time to clean every every nook and cranny in it.

 

Bike starts easy now. Idles good.

 

Problem: Bike does not throttle up worth a hoot. Running at least 1/4 to 1/2 choke helps tremendously. Assuming this is a pilot circuit issue (though I cleaned the pilot circuit very good) or possibly a vacuum issue. I've read several forum posts where folks have had to go through the carbs multiple times to get them right.

 

Things I've done:

-disassembled carbs (one at a time) and cleaned.

-used Seafoam Deep Creek; Carb Cleaner; compressed air; one pilot jets was totally clogged; some gunk in the bottom of a couple of the bowls;

-all jets were sprayed and cleaned several times. I also ran a carb orifice cleaning tool through everything... and ran a small wire through the pilot jets to clean them out. I had good round circles in all jets when holding them up to a light. Sprayed carb cleaner and compressed air through every hole I could find.

 

Reassembled carbs... bike still did not throttle up worth a hoot.

-Sprayed carb cleaner all around looking for a vacuum leak. Didn't really find anything.

-I filled the pilot circuit with Sea Foam Deep Creek and let it sit over night.

-Disassembled diaphragm ends and all rubber is intact and looks good. Cleaned and shined the slides. Sprayed jet.

-removed pilot adjuster screws (screw/spring/washer/oring). Cleaned good. Ends looked good. No deformity.

 

Bike still won't throttle up worth a hoot.

 

*Note: I did not replace any orings or gaskets in the carb.

 

Things I've noticed:

-vacuum ports on the intake boots do not have individual hose caps on them. Carbs 3 and 4 are connected together with a short tube (port to port). Carbs 1 and 2 are connected to a tee which splits off and goes north to the boost port (not sure what the boost port is. I've not researched that one yet).

 

Question: Is that configuration okay? (Note: I've tired reconfiguring it to have individual caps on them. This did not change anything).

 

-Right side carbs (3 and 4): If I remove the vacuum line from either port (Remember, those two carbs have a joined vac line).... the motor immediately tries to die unless I add throttle.

-Left side carbs (1 and 2): If I remove the vacuum line from either port... the motor speeds up a bit. (Remember, those carbs have a common vac line that also goes to boost).

-Right side carbs: With the airbox off... if I spray carb cleaner into the throat of either carburetor the engine starts to die (quickly).

-Left side carbs: If I spray carb cleaner into the throat of either carb throat... nothing happens. (I mean nothing! Engine does not speed up).

 

Question: Why would the two sides respond differently?

 

Currently, engine starts and idles very good. Slides pulse when I try throttling up... but, no power and it just bogs down. If I turn the choke on... of course Idle goes way fast... but, it will rev. I've added choke and rode the bike a little distance and it runs okay. Without choke... it can't even find enough power to climb my driveway.

 

Next Steps:

-My plan is to drain the carbs and fill it full of Sea Foam... turn it over a little bit and let it sit a day or two. Then drain Sea Foam and see what happens.

 

Also... I've NOT sync'd the carbs yet. I don't have a vacuum gauge (yet). Could this be the issue? (I would not think so... but, I refer to those with more carb experience).

 

I welcome your Thoughts? Suggestions? Additional questions?

 

Thanks all!

Paul

[RDawson]

Definitely synch carbs. Have you checked fuel filter, pump, and tank? Are you sure it's running on all four cylinders? They run surprisingly well on three, will idle on two and sometimes even one. Others that know a lot more than me will be along soon. Those are issues I've seen personally.

[BlueSky]

Have you looked down the carb throats while you were blipping the throttle to see if the diaphragms are working in unison? I'd also put some seafoam or gumout with PEA in the gas to help clean the carbs. How does the fuel filter look?

 

You may have corrosion in the ignition wires. The spark plug caps screw off the wires and the wires tend to corrode on the end. Snip a half inch of so off the end of the spark plug wires. Check the other end of the wires at the coils for corrosion at the connections. Weak spark can make a big difference in the way it runs. Also buy yourself an infrared thermometer and check the exhaust pipes temperatures. This may help determining which cylinders are not firing well.

 

Something like this:

 

https://www.walmart.com/ip/Greenpro-Temperature-Gun-Non-Contact-Infrared-Thermometer-Black-Yellow/121562206?wmlspartner=wlpa&selectedSellerId=2837&adid=22222222227062511638&wmlspartner=wmtlabs&wl0=&wl1=g&wl2=c&wl3=169632236150&wl4=pla-276509431121&wl5=9010080&wl6=&wl7=&wl8=&wl9=pla&wl10=114226822&wl11=online&wl12=121562206&wl13=&veh=sem#read-more

[Yammer Dan]

SYNC them!!! And make sure plugs are firing.

[pvw10121]

Update: (actually things I forgot to mention. Robert and BlueSky and YammerDan reminded me)...

 

-installed new fuel filter (previous owner had a new one that he gave me. I replaced it right away)

-fuel pump working good

-installed new plugs... NGK DPR8EA9 gap'd at .033

-compression checked good on all 4 cylinders (all 4 between 200 and 210)

 

(BlueSky... all of the air slides are working in unison. I was lucky with the carb cleanup. All diaphragms were in good shape. Slides cleaned up nicely. Good thought!)

 

-I do have an infrared temp gun. I shot the exhaust tubes and I did notice a difference in temps on left side to right side. That's when I thought I had a problem with the left side and decided to check the compression. (Full transparency here: Honestly, I got derailed from exhaust temp check when I started testing compression (because I forgot to open up the carbs when I first started testing and saw that I had pretty much no compression on the two left cylinders. That's when my heart dropped and I thought I was in for some top end work. Then I came to my senses and opened the throttle ). After chasing that rabbit trail I didn't come back to the looking at exhaust tube temps. I do know that I am getting spark on all four plugs. I don't recall thinking the left side had weaker spark (course... it was pretty bright daylight out).

 

So... updated action plans:

-check temps on exhaust (again)

-clip plug wires back a bit (I have a good feeling I'm going to find something here!)

-sync carbs (I have a buddy bringing me a CarbTune Pro this evening). Will be ordering one soon (Let me know if someone on here has a set of gauges they would like to sell??? ).

 

Question: reading through the forum comments it looks like most folks use the CarbTune vac gauges. Are they really worth twice the money from a set of dial type gauges? (Just curious of your thoughts)

 

Another question: Pilot circuit (air mixture screw) adjustment. Can this be done with vacuum gauges? (Note: I've set everything to 2-1/2 turns out as baseline)

 

Thanks for the replies!

Pwells

 

Paul Wells

[93 venture]

These bikes wont run past idle with out the air filter installed and the intake system has to be leak free. one little leak will make them run funny.

[Pegasus1300]

yes they are worth the money. BUT look on ebay should be used ones on there.

[cowpuc]

Update: (actually things I forgot to mention. Robert and BlueSky and YammerDan reminded me!

 

-installed new fuel filter (previous owner had a new one that he gave me. I replaced it right away) COOL!!!

-fuel pump working good COOL!!

-installed new plugs... NGK DPR8EA9 gap'd at .033 COOL!!

-compression checked good on all 4 cylinders (all 4 between 200 and 210) WAYYY COOL!!

 

(BlueSky... all of the air slides are working in unison. I was lucky with the carb cleanup. All diaphragms were in good shape. Slides cleaned up nicely. Good thoughtDid you check closely along the area where the diaphram meets the carb body? That area as tricked more then one of us lop eared 1st Gen varmints!!

 

-I do have an infrared temp gun. I shot the exhaust tubes and I did notice a difference in temps on left side to right side. That's when I thought I had a problem with the left side and decided to check the compression. (Full transparency here: Honestly, I got derailed from exhaust temp check when I started testing compression (because I forgot to open up the carbs when I first started testing and saw that I had pretty much no compression on the two left cylinders. That's when my heart dropped and I thought I was in for some top end work. Then I came to my senses and opened the throttle ). After chasing that rabbit trail I didn't come back to the looking at exhaust tube temps. I do know that I am getting spark on all four plugs. I don't recall thinking the left side had weaker spark (course... it was pretty bright daylight out). COOL!!

 

So... updated action plans:

-check temps on exhaust (again)? How ya checking em? I have a infra red too but still tend to spit check em like mom use to spit check a clothes iron and it works great - no fancy tools needed.. Most important IMHO is that ya check the headers at the right time = right after start up from cold. If they arent firing at start up and you rev just a little and they hit a couple time your test can be ruined.. Unless, of course,, the thing is not running on all 4 all the time..

-clip plug wires back a bit (I have a good feeling I'm going to find something here! COOL but ohming out the caps is not a bad idea too as long as your stickin in new plugs and got the caps separated from the plugs anyway.. Snipping the wires back is a good start though.

-sync carbs (I have a buddy bringing me a CarbTune Pro this evening). Will be ordering one soon (Let me know if someone on here has a set of gauges they would like to sell??? ). I know,, I am the perverbial old schooler.. I My favorites were the Mercury sticks but those are gone.. Have used Carbtune but not really impressed cause of the tendency for the sliders in the set getting sticky.. Not only that but, for just about the same money a person can get a really nice full set sync gauge set including all the adapters like the one shown in the link below (this is what I have been using successfully for years now and,, if you ever need to sync carbs on an early Wing or Honda 350 or SOHC 750 or many others - you will be WAYYYY glad you have all these adapters). Just my opinion of course. Here is the link to what I am talking about:

https://www.ebay.com/itm/Vacuum-Carburetor-Synchronizer-carb-sync-Gauge-Yamaha-XS-XJ-1100-1200-5mm-6mm/391372275126?epid=2213025123&hash=item5b1f9afdb6:g:vwEAAOSw2xRYaCCS&vxp=mtr

 

I will also post a quick vid of using these gauges below!

Question: reading through the forum comments it looks like most folks use the CarbTune vac gauges. Are they really worth twice the money from a set of dial type gauges? (Just curious of your thoughts read above BUT remember - this is just my opinion in response to your invitation to comment.

 

Another question: Pilot circuit (air mixture screw) adjustment. Can this be done with vacuum gauges? (Note: I've set everything to 2-1/2 turns out as baseline)IMHO no,,not with vac gauges used to sync.. Please read this carefully cause I am mentioning Colortune here = not to be confused with Carbtune = OK? IMHO, What may come in really handy for doing a fairly successful and accurate pilot screw adjustment (aside from purchasing a full blown exhaust sniffer) would be a "Colortune". As shown in the second link below, this tool is used to momentarily replace the plugs one at a time to give you a view at the combustion that is taking place.. You simply install this tool into the plug hole (replaces the spark plug) and watch the flame color and adjust the pilot screw until you get a real pretty blue flame.. Make sense? Here is the link: https://www.ebay.com/itm/Colortune-for-14mm-Spark-Plug/182627858677?hash=item2a8577f8f5:g:MkcAAOSw~XpZSEA9 Also please note - dont just buy this one - you will need to shop a little and make sure your getting the right size and/or getting the adaptors for your scoot (12mm)..

 

Thanks for the replies! ​You betcha PV, YOU are welcome!!

Pwells

 

Paul Wells

 

[luvmy40]

Just to throw another non professional mechanic's $0.02 in here;

 

The fact that spraying carb cleaner into one side's carbs had no effect at all tells me those cylinders are not firing at all. As already mentioned, check your wires, caps and coils with an ohm meter. I like to use an in line spark tester as well. Yamaha has a pretty cool spark tester but I haven't been able to find one for sale at a reasonable price yet.

Edited November 21, 2017 by luvmy40

[bongobobny]

My first thoughts echo others, make sure you are getting a GOOD spark to all 4 cylinders. You can purchase a spark gap tester from just about any auto parts store and should cost less than $15. You should be able to pull a full 0.100" of spark.

 

The best way to set the air richness needle valves is with a CO sniffer monitoring each exhaust pipe. There is a plug on each exhaust pipe for this purpose. The ideal setting is 5.1 from what I remember.

 

There is an excellent DVD out there by Damon Ferarro concerning the proper way to disassemble, clean, reassemble, and set up the carbs. It was made for VMax carbs but they are the same as Venture carbs other than a few differences in the metering, but that is also brought out in the video. It's well worth the investment, and when bought along with the engine rebuild video he gives a discount price. The carb video is around $15 or so...

 

EDIT: I was spelling his name wrong! Hey, I'm an old fart and my brain is sometimes misfiring! Here's a link to a thread that has his email address in it...

http://www.venturerider.org/forum/showthread.php?119186-Bought-Carb-Rebuild-Video-by-Damon-Ferraiuolo&highlight=Damon

Edited November 21, 2017 by bongobobny

[Chaharly]

So what do you and @cowpuc mean when you say ohming the plug caps and clipping the spark plug wires back? I'm a youngn and they never taught us that in tech school???

 

clip plug wires back a bit (I have a good feeling I'm going to find something here! COOL but ohming out the caps is not a bad idea too as long as your stickin in new plugs and got the caps separated from the plugs anyway.. Snipping the wires back is a good start though.

[BlueSky]

So what do you and @cowpuc mean when you say ohming the plug caps and clipping the spark plug wires back? I'm a youngn and they never taught us that in tech school???

 

clip plug wires back a bit (I have a good feeling I'm going to find something here! COOL but ohming out the caps is not a bad idea too as long as your stickin in new plugs and got the caps separated from the plugs anyway.. Snipping the wires back is a good start though.

 

The spark plug caps screw off the plug wires. Then you can check the resistance of the cap. The OE cap has about 9,000 ohms of resistance. Sometimes they also corrode inside and the resistance will increase. The joint where the wire screws into the cap is not water tight and gets moisture in there causing the copper wire to corrode. It is typical to find that the wire is corroded there and cutting off a half inch or 3/4 inch will get past the corroded wire and improve the spark. NGK.com has replacement spark plug caps for our bikes and they have 5,000 ohms resistance.

[Chaharly]

The spark plug caps screw off the plug wires. Then you can check the resistance of the cap. The OE cap has about 9,000 ohms of resistance. Sometimes they also corrode inside and the resistance will increase. The joint where the wire screws into the cap is not water tight and gets moisture in there causing the copper wire to corrode. It is typical to find that the wire is corroded there and cutting off a half inch or 3/4 inch will get past the corroded wire and improve the spark. NGK.com has replacement spark plug caps for our bikes and they have 5,000 ohms resistance.

 

So would that mean I need spark plug wires with 4k resistance? To make it 9000 again?

[BlueSky]

So would that mean I need spark plug wires with 4k resistance? To make it 9000 again?

 

I don't think so. I think the NGK caps will be okay but some of the members have more experience in this area than I do. The NGK caps should cause a hotter spark.

[garyS-NJ]

I think the lower resistance might cause more radio noise (if you still got one, who does??). There's stuff written on this and I forget the answer but I thought it best to keep them all at the 10K number. And if my memory serves me right there is a little resistive element in there which can open or corrode (or maybe I just had a day dream, I have a bunch of bikes and remember those little resistors in one of them).

 

Sent from my VS987 using Tapatalk

[camos]

So would that mean I need spark plug wires with 4k resistance? To make it 9000 again?

I'm pretty sure plug wires with resistance are carbon core automotive ones and are not what you should be using. Instead look for solid core wires. All the resistance is in the cap resistor. As far as radio interference is concerned, the R on the spark plug stands for resistance which is supposed to cut the radio interference.

 

There was a fairly lengthy discussion on the Virago site quite a few years ago about this same corroded resistor issue and quite a few people recommended replacing the resistor with a suitable length of #10 solid copper wire. It worked and many claimed that it gave a stronger spark.