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83 Venture Bobber builds


Bassett

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Exactly right, however in this case, bobberizing it will make a good case for getting rid of the air box because it is too big and ugly to keep.

 

My suggestion would be to use PVC pipes out each side to cone filters and rather than re-jetting mess with throttling the air intake using washers to get it back to near the OEM restriction. The air box is large but the actual inlet is quite small. Anyway, I think it would be a lot easier to adjust that way than re-jetting would be.

 

 

 

Yes! Any threads on this process???

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Yes! Any threads on this process???
Very few Ventures have been modified to this degree and I doubt that there are any threads which detail the process. I would suggest that you simply build what you like and get the instrumentation to measure air/fuel ratios and figure out how to make it run right.

zag

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Very few Ventures have been modified to this degree and I doubt that there are any threads which detail the process. I would suggest that you simply build what you like and get the instrumentation to measure air/fuel ratios and figure out how to make it run right.

zag

 

Yes! Any threads on this process???
Not disagreeing with zagger on this but there are two ways to deal with this issue. One is to re-jet the fuel flow and the other is to restrict the air flow to match the engine requirements. The easier, less expensive method is controlling the air flow. IMHO.

 

I have seen a couple of builds somewhere over the years that used either plastic tubing/pipe or copper tubing out the sides to replace the air box. Adjusting the airflow should not be too complicated. Measure the inlet area on the air box and divide by 4 should give a reasonable approximation of the amount of air needed to at least get the motor running well enough to tune from there. A washer/baffle installed like a butterfly valve in the inlet will allow an easy enough temporary adjustment to find the optimum setting.

 

One good thing about adjusting air flow this way is that at a later date you could always re-jet if desired. It seems that most re-jetting to adjust for greater flow, usually due to changing the filter and exhaust, ends up getting a little more power but worse mileage. Not to mention being more expensive.

 

A possible down side to using open filters is what happens when it rains?

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One is to re-jet the fuel flow and the other is to restrict the air flow to match the engine requirements. The easier, less expensive method is controlling the air flow. IMHO.

 

I totally agree. I restricted flow through the four intake air filters by adding a large steel washer inside the neck of each air filter. I machined the ID of the washer to set the intake pressure drop so that I could use stock jetting. Power is good and mileage is in the mid-forties. I believe that the ID is quite important and you cannot simply stick in whatever standard washer you happen to find. I looked through my notes from 10 years ago and it appears that the hole size I used is 1 inch. I have lots of pages of pressure drop calculations and comparisons to the inlet size on the stock filter box. The washer orifice size inside each air filter sets the intake pressure drop, but I should mention that I also have Vboost valves from a Vmax and have found that the best setting for general riding is to have these valves just slightly cracked open. This setting slightly distributes each cylinder intake pulse a little bit beyond the single carb that would supply air/gas in a normal Venture. Obviously, this setup slightly affects the intake pressure drop calculations and the airflow numbers through a single carb. I only mention this to give you a complete picture of my situation.

 

Heavy rain entering the filters might become a problem if you are stopped. On my bike, the filters are somewhat protected by the bike frame, headlights, etc. but I cannot say if that is enough protection for a real soaker. Of course, I try to avoid riding motorcycles in heavy rain anyway! If the bike needs to sit outside in the rain, I have four plastic drinking cups stored in the bike bag which can be placed over the filters to prevent water from entering. My filters point upward so it is not a problem for the plastic cups to just sit there.

zag

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I totally agree. I restricted flow through the four intake air filters by adding a large steel washer inside the neck of each air filter. I machined the ID of the washer to set the intake pressure drop so that I could use stock jetting. Power is good and mileage is in the mid-forties. I believe that the ID is quite important and you cannot simply stick in whatever standard washer you happen to find. I looked through my notes from 10 years ago and it appears that the hole size I used is 1 inch. I have lots of pages of pressure drop calculations and comparisons to the inlet size on the stock filter box. The washer orifice size inside each air filter sets the intake pressure drop, but I should mention that I also have Vboost valves from a Vmax and have found that the best setting for general riding is to have these valves just slightly cracked open. This setting slightly distributes each cylinder intake pulse a little bit beyond the single carb that would supply air/gas in a normal Venture. Obviously, this setup slightly affects the intake pressure drop calculations and the airflow numbers through a single carb. I only mention this to give you a complete picture of my situation.

 

Heavy rain entering the filters might become a problem if you are stopped. On my bike, the filters are somewhat protected by the bike frame, headlights, etc. but I cannot say if that is enough protection for a real soaker. Of course, I try to avoid riding motorcycles in heavy rain anyway! If the bike needs to sit outside in the rain, I have four plastic drinking cups stored in the bike bag which can be placed over the filters to prevent water from entering. My filters point upward so it is not a problem for the plastic cups to just sit there.

zag

 

 

Science Zag! Crazy how the beast runs!!

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For Yamaha to get around it is easy they just designed the whole system to work together, they are not using an aftermarket off the shelf tach.

 

Sometimes on a tach you can lie to it about what it is connected to.

I once had a car with wasted spark ignition on a V8, I told the tach it was connected to a 4 cyl to get it to read correctly. If your tach has a selection for 2 cycle engine, use that it it will then read correct. Just have to play with what they give you till you find what works out. I often lie to various pieces of electronics to get the end result that I am after.

 

Kind of like lying to your girl friends to get what you wanted back in the day!

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I had hoped so too, but it didnt work.

 

:sign07::hijacked: :sign It wasnt me:Yeah buy a bunch of Yamahammer riding lunatics..... damn my friends lied to me... :sign back to topic: :sign It wasnt me: :sign13:Like the idea there I was wondering how to cover big things without having to mess with that big brown paper stuff... :You_Rock_Emoticon:

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