Fuel pressure regulator?

jpring · Post by **jpring** » Wed Nov 02, 2005 9:05 pm

Going through the Dellorto 36mm carbs on the Paso, Doing the carb "cuddle" and got everything working decent, I did have a occasional stumble or miss, and was thinking at the time possibly too much fuel was returning to the tank causing the carbs to starve for fuel some? So I put the fuel regulator back on, but on the return line. The bike did seem to run beter, but then it just up and quit... :umm: . And smells gassy, so obviously I must have flooded it by restricting the return line. Should I put the regulator on the supply side of the line? And what should I set the regulator to? It was originaly on the supply side and set to "2". Maybe I should have left that part alone

.
**Update** Tonight I returned the regulator to the supply side, right after the fuel pump, put it on "2" and was able to get restarted. It seems to be running very well except for the stumble and miss now and again, I'm suspecting a bad front cylinder spark plug cap. Does anyone know if the plug wires unscrew from the coils? I didn't want to try and end up damaging them.

Post by **Skins** » Thu Nov 03, 2005 8:02 am

The DellOrtos on my bike work fine without either fuel pump or regulator, and something tells me that was the way they were designed to work. Gravity is all they need. You might find the front cylinder works better (it's usually the one to stumble if anything's wrong) if you ditch the pump and regulator.

Rodney · Post by **Rodney** » Thu Nov 03, 2005 8:58 am

i trust you have no exhaust leaks and the float seats are good as either of these will cause a miss or splutter thought the carbie or carbies. i hope you have the "y" piece return around the fuel pump as otherwise you build up way to much pressure

Rodney

Post by **jcslocum** » Thu Nov 03, 2005 12:11 pm

No fuel pump required for the Dellorto's. Removing it might not cure the stumble tho. The pressure fomr the pump will over time change the float height so you will want to check that before digging into anything else.

Check the voltage at the coils when idling too. Could be a weak spark. Check the Paso FAQ digest for a discussion on the Paso wiring.

jpring · Post by **jpring** » Thu Nov 03, 2005 7:26 pm

I was going to check the float hight, but don't have a good way to do that... I think I need a fitting with a clear piece of fuel line to connect to the bottom of the carb bowl to set the float hight? The right side carb sits at a angle so it would not be accurate to set it on the bench. I thought about removing the pump, due to the bowls being lower than the fuel tap, but didn't. I'll do that tonight, I'm assuming I can plug the return fitting on the fuel tank if not using the fuel pump? Still need to find out if the coil wires will unscrew from the coils or not, I have new wires but don't want to damage a coil twisting on the wire to find out.

Post by **Skins** » Thu Nov 03, 2005 7:57 pm

I can't help you with these specific questions, Jeff, and I'm just too busy at the moment to dig into my own bike to find out. But I will in a couple of days if you haven't found the answers yet.

jpring · Post by **jpring** » Fri Nov 04, 2005 2:48 am

That's no problem Skins, I thank you very much for all the help you've provided

... I still have a very slight misfire right off idle, but it will only happen maybe once in twenty tries. So I think it's ok for now, I'm going to put it back together and maybe get on the road one more time. Maybe when it starts snowing I'll get into it a little more and change the timing belts, check the floats, ignition, ect. oh, I did remove the fuel pump and plug the return to the tank, works perfect!

Post by **Skins** » Fri Nov 04, 2005 3:03 am

Great stuff, Jeff. Now just ride carefully till you really know the bike. Nine out of ten prangs happen on a bike that's new to the rider. If you brake going into a corner, use the rear brake also to keep her steady.

jpring · Post by **jpring** » Fri Nov 04, 2005 5:19 am

Thanks! It's back together tonight and hoping for a decent day tomorrow so I can do another ride, I think I'm going to see more power with the carbs "cuddled"

. It's nice to have the fairing back on too, the Paso isn't quite as pleasing to the eye with the plastic taken off

.

Post by **Skins** » Fri Nov 04, 2005 5:57 am

Well, I hope the weather's good tomorrow. Let us know how she goes. It can take a while to get the carburation just right. I've read that tuning carburation for the road is often the most difficult job one can do on a motor, and often can only be done by the owner (A Graham Bell, 'Four Stroke Performance Tuning' Haynes, 1998) because only he or she potentially has the time. It sure took me many days, at a couple of hours a day, and many pages in a pocket notebook. Most people accept that their carburation is just average, and that by working together their carbs give a good enough result. But if you can get each one just right, and both doing it exactly together, there is a real boost in performance.

jpring · Post by **jpring** » Fri Nov 04, 2005 5:43 pm

I just got back from my 2nd ride on the Paso. It's 44 degrees with light rain, only snow would have stopped me from finding out if the hours spent where worth while. I managed to put on a short 10 miles in the rain and was surprised how well she handles even in the wet. The flat mid range is still there, but seems worse now with the exception of not coughing and stumbling

, although the low end power has improved. I previously moved the needle clip from the lower position to the middle thinking the carbs were slightly rich. I may need to return the clip where it was or purchase different needles. The K&N's might be pulling too much air? I don't mind the down time or qwerks, I really enjoy the project, on the bright side what I originaly pushed into the garage I can now drive out...

Rodney · Post by **Rodney** » Mon Nov 07, 2005 12:26 pm

you may have to play with a few different jets as the exhaust plays a big part in it you may find that you are creating more or less back pressure with non standard exhaust. i my self had to change jets becuase i changed to staintunes put unfortunately the bike came off its sidestand and damaged one (they do not make them anymore) so i have just got a set of contis and may have to change jets again.

Rodney

jpring · Post by **jpring** » Sat Nov 12, 2005 1:18 am

Slowing down and taking my time paid off. I went through the Dellortos once again, I measured the floats and found them to be off a bit, I set both to 18mm. I cleaned the carb jets and passage ways once more, assembled and "cuddled" the carbs. I removed the fuel pump, blocked the return to the fuel tank and routed new lines. I also learned a couple things that helped fairing assemby, I put a very thin layer of grease in the slots the oil coolers slide into. This aided alot with instalation and removal. Second, I was missing two plastic washers for the fairing screws, I used a left over piece of 1/4" black rubber fuel line and cut off a couple thin rubber washers from it, they fit quite well. I headed out for another test ride ( at this point trying not to expect too much :toofar: ) I felt a difference in power just leaving the driveway? Once out on the road the Paso pulled hard in every gear, no sputters, no stumbles, just smooth and responsive all the way through!!!

Although the fairing isn't difficult to remove, I'm happy to be leaving it on for a while now...

Post by **Skins** » Sat Nov 12, 2005 2:05 am

Good stuff, Jeff! There's probably more to come too!