G1 Predator 670 Vtwin

[slonomo]

Originally Posted by PharmGuy85

Have you read the Vegas Carts tach install guide. The mention that even their tach has issues with the 670 and that ordering a different set of ignition coils seems to fix this issue. I just ordered a set off Amazon.

Thanks for the response. Yeah I read that, and also on other sites. At this point I really don't "need" a tach. It would be nice to know exactly what rpm I'm operating at, but as long as I'm not doing high speed runs I'll be ok. I know that at 25 mph my cart should be in the 4200 rpm range. 25 mph satisfies my needs lol. I'm past my "as fast as possible" stage The real reason is I'm not anxious to take the thing apart lol

[kellett5261]

Originally Posted by slonomo

Thanks for the response. Yeah I read that, and also on other sites. At this point I really don't "need" a tach. It would be nice to know exactly what rpm I'm operating at, but as long as I'm not doing high speed runs I'll be ok. I know that at 25 mph my cart should be in the 4200 rpm range. 25 mph satisfies my needs lol. I'm past my "as fast as possible" stage The real reason is I'm not anxious to take the thing apart lol

I had the same issue with my Equus Tach. super easy to get it working, it does involve taking off the fan shroud to get to the coil wire, I cut the wire and taped in with the supplied green wire and routed my wire up front to the tach, no more jumpy Tach

[slonomo]

Originally Posted by kellett5261

I had the same issue with my Equus Tach. super easy to get it working, it does involve taking off the fan shroud to get to the coil wire, I cut the wire and taped in with the supplied green wire and routed my wire up front to the tach, no more jumpy Tach

You didn't have to change your coils?

[JPonLKN]

I have an Equos Tach, wired straight to the coil on my 670, not the induction clip, or wire around a plug wire and it works fine...no jumping around. I tried it with the clip first, and it bounced all over the place.

[slonomo]

Man, I don't have the orig wiring from the tach.

[PharmGuy85]

Slo, I think I want to go ahead and replace the fuel pump on my 670 before the install. Do you think any Briggs mikuni 16-26hp or honda gx series would be a direct fit?

[slonomo]

Originally Posted by PharmGuy85

Slo, I think I want to go ahead and replace the fuel pump on my 670 before the install. Do you think any Briggs mikuni 16-26hp or honda gx series would be a direct fit?

This is the one I used, perfect fit. Works great. I've used this type of fuel pump on every big block engine I've done, never any problems.

[kellett5261]

No sir keep you factory coil. ill take a picture for you when I get home if you want. super easy, I just cut the spade connector off and tapped in there with the green wire for the tach. Never been an issue since.

[kellett5261]

Originally Posted by slonomo

Since I'm not a big fan of Chinese small parts, I decided to check all the little parts in the fuel system. I discovered a filter in the vacuum pulse line. I took it off and opened it up....what the.... It has some stainless steel shavings like what you'd see in some kitchen pot scrubbers. WTH??? Also inside was some kind of gritty plastic biscuit thing that literally disintegrated into tiny little pieces. I just took all that crap out of there and used a piece of rubber fuel line with no obstructions.

On a side note, the piece of fuel line I used in the photo was too short and I ended up cutting a new piece. The line has to thread through a metal bracket for the fuel pump.

Did this fix your issue? mine has been running like crap lately, I adjusted the carb and changed the plugs, ran much better at idle (1100-1200 rpm) but randomly pops/back fires at higher rpms, pissing me off. sounds like chitty chitty bang bang going down the road lol i didnt think to pull apart that crappy vacuum line, I did on my first engine but ill check mine when I get home today

Originally Posted by slonomo

After tuning the carb it was running better than ever. When I tuned the two pilot circuits I started with the screws 2 turns out, ran the engine at 3000 rpm to warm it up. I used a laser thermometer to monitor engine and exhaust temperature.

On this engine the right side main jet is 108 and the left is 105, so I paid attention to the exhaust pipe temp to get the jetting balanced. I've never done one this way but read about it so I thought I'd give it a try. The idea is that a leaner air/fuel mix will be hotter than a rich one. So the goal was to tune the pilot jetting by sound and feel then adjust to balance the the exhaust temps. It actually worked quite well. The area of the exhaust pipe I checked was about 1" from the exhaust flange on the topside. Temps were fluctuating but were maxing out at about 570 degrees F. Surprisingly I could see the temps change with every 1/4 turn of the pilot screw.

You didn't happen to do a video on this did you? I can typically get it close without a heat gun but i'd like to try this on mine, i feel it would really dial this thing in.

Now the cart will idle smooth, has immediate response off idle, good seat of the pants power feel, and good acceleration. No hesitation, no bogging, no stalling. And guess what? It doesn't run the fuel bowl dry

[slonomo]

Ever since I did all that the 670 has started good, runs good, idles good, etc.

The laser thermometer is something of a novelty to some, but I swear by it. You'll never get the cylinder temps perfect, but I got mine pretty close. It's about as much tech as I can throw at this simple engine.

At first, I had flooding issues on the right side cylinder when facing the crank. It's funny, I had the same issues on my 23 Vanguard. Anyway, I did take the jet from that side out and went down a size, the 670 came with a jet kit for high altitude. It was only 2 numbers smaller.

I also upgraded the spark plugs to double platinums.

Tuning the carb should be done once the engine is warm. I zeroed down the idle air adjusters and started at 1.5 turns out. I adjusted them evenly until the engine "sounded" good. Then I adjusted the idle down around 1000 rpm. Then I got the laser thermometer out and played with the jets until I saw temps on the cylinder and exhaust pipe nearly the same. I didn't record how many more turns I did on the screws.