Need your help
#11
09-20-2012, 10:05 PM
Join Date: Sep 2012
Posts: 23
Likes: 0
Received 0 Likes
on
0 Posts
try this.... On the right hand side you have a tube going from the air box into solenoid and then there is a tube from the selenoid into the carbs. Remove the selenoid and connect those two tubes together. Remove all tubes from the other side of the bike which are coming from the front of the bike.. . All the small tubes and solenoid are only working when u are riding under 12kph.
To answer your question directly... and assuming you have checked all the fuel related problems (including fouled plugs)...
Yes. Open exhaust does affect the fuel air at the engine. It's complicated and relates to backpressure keeping expelled and unburned fuel in the chamber a hair longer for more complete combustion. Yamaha's are well know for this very problem. It is very common to have to rejet the carbs (or change injectors) when an open exhaust is installed on a stock bike. One of the cures (on certain bikes) is changing the crancase ventalation as well, but this gets complicated and probably does not apply to your situation.
Bottom line is severe reduction of backpressure affects fuel combustion, and the smaller the cc's, the greater the affect. Also reduces low end torque by a small amount. If you are going to run open pipes, rejet and run hotter plugs. The unburnt fuel will foul the standard plugs quickly. And do not open the gap on the plugs to compensate... you run the risk of contact with valves or pistons if your tolerences are very small.
I would replace the baffle or install an aftermarket exhaust, and than readdress the problem after that. All of this is assuming, as I said earlier, that you have already ruled out the other problems suggested in this forum.
Yes. Open exhaust does affect the fuel air at the engine. It's complicated and relates to backpressure keeping expelled and unburned fuel in the chamber a hair longer for more complete combustion. Yamaha's are well know for this very problem. It is very common to have to rejet the carbs (or change injectors) when an open exhaust is installed on a stock bike. One of the cures (on certain bikes) is changing the crancase ventalation as well, but this gets complicated and probably does not apply to your situation.
Bottom line is severe reduction of backpressure affects fuel combustion, and the smaller the cc's, the greater the affect. Also reduces low end torque by a small amount. If you are going to run open pipes, rejet and run hotter plugs. The unburnt fuel will foul the standard plugs quickly. And do not open the gap on the plugs to compensate... you run the risk of contact with valves or pistons if your tolerences are very small.
I would replace the baffle or install an aftermarket exhaust, and than readdress the problem after that. All of this is assuming, as I said earlier, that you have already ruled out the other problems suggested in this forum.
Plea, everybody keep the ideas coming just incase my current options don't work.
Ps. Can anybody tell me why my 2 and 3 carbs have a 136 jet in them instead of a 135 like the manual calls for and the 1 and 4 jets are still stock 138's?
#12
09-20-2012, 11:21 PM
Junior Member
Join Date: Sep 2012
Location: Cork Ireland
Posts: 20
Likes: 0
Received 0 Likes
on
0 Posts
I wouldn't worry too much about the jetting shaggy, that could have been done for any number of reasons, after market exhaust being one....maybe tha last owner wanted a particular power demand for his own use ! Honda's can take a fair amount of different settings without too much bother. By the sounds of what you're saying I reckon its an air problem...try all options, take out the air filter and run the bike, restrict the air..even spray a wee bit of WD40 or carb cleaner around the air intakes...you'll find it eventually, whether its too much or too little.Just one small bit of advice....remember what the bike is for and what use/abuse it may get ! you do not always need top end performance from a bike that may get only small usage...........we have a saying here " keep things simple...simple works "
#13
09-21-2012, 03:23 AM
Join Date: Sep 2012
Posts: 23
Likes: 0
Received 0 Likes
on
0 Posts
Thanks headhuntter, I will definitely give these options a try and hopefully it can figure it out. Im not really worried about the top end so much as the bike literally wont get past about 40 to 45 mph without falling on its face no matter how hard I try. I mean sitting still its smooth and actually is pretty responsive. The bike is my wifes bike so trust when I say im glad the bike wont do 160 mph, but she atleast needs to be able to enjoy it if she's going to ride it.
#14
09-21-2012, 08:40 AM
#15
09-21-2012, 09:35 AM
Junior Member
Join Date: Sep 2012
Location: Cork Ireland
Posts: 20
Likes: 0
Received 0 Likes
on
0 Posts
On a lighter note ....my wife wanted to learn to ride a bike about 15 yrs ago...so brought her to a lonely back road on a finely tuned yamaha race bike...told her what to do...lo and behold she dropped the bike after 20 yards and never wanted to try again
....I value my freedom more than a yamaha, money well spent ( sorry Shaggy for off topic ) but I'll be watching your attempts and hopefully all will go right
....I value my freedom more than a yamaha, money well spent ( sorry Shaggy for off topic ) but I'll be watching your attempts and hopefully all will go right
#16
09-24-2012, 06:18 PM
Join Date: Sep 2012
Posts: 23
Likes: 0
Received 0 Likes
on
0 Posts
Ok, so today was the first day off since we all talked about my problems. I got the bike all back together after really cleaning the carbs and making sure I didn't miss anything and lo and behold its still spitting from about 40 mph and wont get much past 45. I tried routing the ram air tubes like the OP mentioned to bring more air into the carbs and that seemed to make it worse, so I then took some electrical tape and restricted the air intake and..... at first I restricted it to much and she wouldn't climb so I put multiple small increments and after tearing a couple of layers of electrical tape off she came to life and climbs like a rocket. She ran up to about 85-90 mph with no problem but it didn't take long and I lost some tape and she went back to spitting. So I have a stock exhaust coming tomorrow untill I can get a good set of jets, but the bottom line is I think we've figured it out. So, thank you to everybody for all your advise and tips. Ill keep everybody updated.
#17
12-13-2012, 07:02 PM
Join Date: Sep 2012
Posts: 23
Likes: 0
Received 0 Likes
on
0 Posts
Its been awhile since I updated this thread, so here it is. The bike has been sitting quite about lately due to me working alot and the wife having the kids and not able to ride, but i have been starting the bike just to keep the blood flowing. I ordered a carbjet kit and installed it today and took it out for a ride afterwards and all I can say is holy $h!+. That is how I expected the bike should.
