Early 83's engines same as VMax?

[a1bummer]

Not to long ago, someone mentioned that the early 83's were built to the same specs as the VMax engines. Anybody have any input on this. Can anybody confirm this? If so, does anybody know where the serial numbers end/begin?

 

I keep hearing people say that the MKII 1300's weren't as quick or powerful as the MKI 1200's. I would think the 1300's would be quicker due to the extra 100cc's. Some say they were all detuned half way through 1983.

 

Anybody have anything more to go on than just speculations? I'm looking for real facts and data here.

 

Just bouncing some ideas around in my head.

 

Thanks,

Bill

[Kirby]

The Vmax was developed from the early Venture engine, not the other way around. I think the first year Vmax was1985.

[jet3279]

v max's have different cam timing, lift and duration. and the valve springs are stiffer. the 83 tci had dirrerent ignition timing, so they were the quickest of the 1200's. I don't think compression ratios changed for the 1200's. my dad has an 83, and he has more power and gets better fuel mileage than my 87.

[Prairiehammer]

Not to long ago, someone mentioned that the early 83's were built to the same specs as the VMax engines. Anybody have any input on this. Can anybody confirm this? If so, does anybody know where the serial numbers end/begin?

 

I keep hearing people say that the MKII 1300's weren't as quick or powerful as the MKI 1200's. I would think the 1300's would be quicker due to the extra 100cc's. Some say they were all detuned half way through 1983.

 

Anybody have anything more to go on than just speculations? I'm looking for real facts and data here.

 

Just bouncing some ideas around in my head.

 

Thanks,

Bill

 

The 1983 Venture engine was unchanged (according to part numbers) throughout its production. There seems to be no evidence of 'de-tuning'.

 

The 1300, in addition to the displacement increase, also had a different tune than the 1983. The carbs have different jetting, different slides and springs and the cam lift (reduced) and duration was changed for more torque. But the biggest difference between the 1200 Ventures and the 1300 Ventures (aside from appearance and convenience/luxury features) was the weight. The 1983 Venture Standard weighed 734# wet. The 1986 Venture Royale weighed 783# wet. Nearly fifty pounds more! Approximately a 7% weight gain versus an 8% displacement gain (1198 v. 1294cc).

 

The heads and carbs are different when comparing the 1983 Venture to the 1985 VMax (perhaps only because of the increased valve size). The 1983 1200 Venture, 1985 VMax and the 1986 1300 Venture all share the same Mikuni BDS34 carbs (according to the service manual), but the jetting is substantially different when comparing the three. The jets are generally bigger on the VMax; and slightly larger on the 1300 compared to the 1200 Venture. The 1983 1200 Venture and the 1985 VMax have the same cam LIFT (again according to the service manuals specifications, but the part numbers are different). Perhaps the VMax cam has a longer duration and different valve timing. Of course, the Vmax had the V-Boost intake system, for a substantial power gain.

 

The 1200/1300 intake and exhaust valves are the same, but the 1985 VMax intake and exhaust valves are larger by approximately 1-1.5 mm.

 

The 1983 1200 and the 1986 1300 have identical ignition timing curves (according to the service manuals), the difference between the two versions is where the engine vacuum readings are taken.

 

Finally, the transmission gear ratios are different between the Venture and the VMax. The Vmax secondary and transmission gears are numerically slightly higher (greater acceleration). The final drive is a 'lower' gear on the VMax, too. The VMax weighs variously 100 pounds less than the 1983 Venture.

Edited August 27, 2014 by Prairiehammer

[dingy]

Pistons in VMax have different doming profile than Ventures, picture attached.

 

There have been a number of rod revisions in the VMax & probably Ventures.

 

Crank in all 1st gen VMax & Ventures is same p/n. Rotor is interchangeable but diff. p/n. may be lighter .

 

The only difference between Venture 83 motor & 84/85 motor is TCI that I am aware of. Also minor difference in carb vacuum port location on #2 carb. 83 had port above butterfly. 84 - 93 used sync port for TCI vacuum. An 83-89 TCI can be used on an 83 motor with vacuum relocation. An 83 TCI is difficult to put on an 84-89 Venture due to vacuum port is not there on later carbs.

 

Vmax blocks have an additional oil galley feed line than dumps oil near stator area.

 

Heads between VMax & Venture is where a lot of power difference lies. In combination with head difference, the cylinder cover for draining coolant from cylinder jackets is different. Different, but interchangeable valve covers.

 

Air intake is improved on VMaxs in addition to all VMaxs have 35mm carbs. 83-85 Ventures had 34mm carbs. Jetting is much different. Mains are 117.5 or 125 on Ventures and 150 or 152.5 (may be others?) on VMax.

 

Exhaust system is much improved for power on VMax. They will not fit on a Venture though due to mono shock difference.

 

Transmission gearing is almost identical ratios between Venture & VMax. Not enough difference to be worth experimenting with swapping.

 

Final drive is higher ratio on VMax, one less tooth on pinion.

 

In regards to another post you had on keeping middle gear set with transmission set, it is best to keep a used set together. Each pair will have a slightly different wear pattern. Ebayer's will break parts down to lowest denominator, they are interested in what will sell, not what is a mechanically sound practice.

 

All side covers will interchange from VMax TO venture. The 83-85 Venture clutch cover will NOT fit on a 86-93 Venture or VMax, it is slightly narrower.

 

I believe the later VMaxs had a spin on auto oil filter, not positive though.

 

Gary

[Michel]

On this link you can see also a piston 1200 venture and 1200 v max.

 

http://1200venturev4.unblog.fr/2013/09/01/xxxxxxxxxxxxxx-pistons-xxxxxxxxxxxxxxx/

Edited August 27, 2014 by Michel

[Beau-Kat]

I believe the later VMaxs had a spin on auto oil filter, not positive though.

 

Gary

 

Yes.

My 1998 has the spin on filter.