Moto Guzzi Round Head Tonti Frames

Purpose, disclaimer, and other resources

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Purpose

The purpose of this page and the information it contains is to provide useful or hard-to-find information about the round head Moto Guzzi Tonti frame motorcycles. The term "Tonti" refers to the engineer who designed the frame, Lino Tonti.

Disclaimer

I have done my best to present correct and accurate information. However, I do not consider myself an expert in the area of Moto Guzzi motorcycles nor Tonti Framed models in particular. If you find this information useful, I'm glad to be of service. If you see something that is incorrect, I'd appreciate it if you would send me a quick email detailing the mistake. If you use any of the information I have provided, you do so at your own risk. I take no responsibility for the accuracy of nor the consequence of using any content on this page.

Other resources

Of course, all of this information can be gleaned from alternative sources. For reading material, get the factory workshop manuals, the factory spare parts catalog, the Haynes book (Moto Guzzi 750, 850 & 1000 V-Twins Owners Workshop Manual; ISBN 0856963399), or Guzziology by Dave Richardson. For serious online discussions, try the GuzziTech and Guzzi Exchange Australia news groups. For new parts, I recommend MG Cycle or your local dealer. For used parts, call Mark Etheridge of Moto Guzzi Classics. ebay is also good place to look. If you want to be a member of an excellent motorcycle club, I recommend the Moto Guzzi National Owners Club.

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Crush washers

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Fiber or aluminum crush washers are used to make seals in numerous locations. Here are the applications and inside diameter sizes used on nearly all round head Tonti frame models:

The I-Convert uses many additional crush washers. Here are the applications and inside diameter sizes for it:

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Header pipe flange securing studs

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The original studs are 8 mm x 1.25 mm x 42 mm. I purchased some replacement 40 mm long 18-8 stainless steel studs from McMaster-Carr (item number 93805A359). They work great although next time I would purchase 50 mm studs and remove the excess as the 40 mm are just a bit short.

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I-Convert ATF pump O-ring size

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The physical dimensions of the o-ring (MG# 90706409) that seals the ATF oil pump to the timing chest is as follows:

• 40 mm ID x 2.5 mm thick

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I-Convert ATF pump seal size

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The physical dimensions of the seal (MG# 90401423) are as follows:

• ID: 16 mm
• OD: 22 mm
• Width: 4 mm

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I-Convert replacment oil lines

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I extracted much of this information from Paul Linn in personal communications.

The operating pressure of the hydraulic oil for the torque converter is 25-29 PSI. Because it is this low, standard oil lines can easily replace the stock lines. There is no need to source new fittings. Just cut the existing pressed-on hose clamps off, replace the hose, and clamp in place. As is mentioned in Guzziology, the line running from the reservoir tank to the inlet (left) side of the hydrualic pump is under suction. Be sure to use a thick-walled hose in this application to prevent it from collapsing.

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I-Convert transmission O-ring sizes

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I-Convert trasmission seals

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Output (layshaft) seal

The physical dimensions of this single lip seal (MG# 90403547) are as follows:

• ID: 35 mm
• OD: 47 mm
• Width: 7 mm

Input (clutch) shaft seal - rear

The physical dimensions of this single lip seal (MG# 90401630) are as follows:

• ID: 16 mm
• OD: 30 mm
• Width: 7/6.5 mm

Input (clutch) shaft seal - front (small, fits into transmission case)

The physical dimensions of this single lip seal (MG# 90402838) are as follows:

• ID: 28 mm
• OD: 38 mm
• Width: 7 mm

Input (clutch) shaft seal - front (large, fits into clutch case)

The physical dimensions of this single lip seal (MG# 90404563) are as follows:

• ID: 45 mm
• OD: 60 mm
• Width: 7 mm

Clutch area seal

The physical dimensions of this single lip seal (MG# 90402535) are as follows:

• ID: 25 mm
• OD: 35 mm
• Width: 7 mm

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Main bearing seal sizes

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Front main seal

The physical dimensions of this single lip seal (MG# 90402839) are as follows:

• ID: 28 mm
• OD: 38 mm
• Width: 7 mm

Rear main seal

The physical dimensions of this single lip seal (MG# 90405367) are as follows (Viton seals with serrated lips are recommended):

• ID: 53 mm
• OD: 68 mm
• Width: 10 mm

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Mikuni round slide tuning baseline

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Thanks to Mike Tiberio for providing this information. In his own words...

Recently there was a Mikuni carb setup for a SP 1000 on ebay. I bid, but didn't win. I contacted the seller (Steve Braun), and asked if he would share the jetting information he learned in setting them up.

These carbs are available from pro-flo.com for $90 new, but without a baseline, you could easily spend that much buying tuning parts to get this close. He sent me the following info (with selected edits by me).

Here are the particulars for the Mikuni setup for the SP 1000.

• VM32 round slides
• 2.5 Cutaways
• 159P0 needle barrels (I think he means atomizers or needle jets here)
• 6DH3 needles clipped at the middle position
• 170 main jets
• 35 pilots
• 2.0 air jets

Some notes:

• The SP1000 was completely stock.
• Both intake manifolds are # 14115002 (Right Side). The left carb won't fit with stock left manifold, the carb hits the motor.
• The intake manifolds should be blended on the inside to match the carb opening.
• The air cleaners are K&N RU-1730.
• The installation fits very neatly if the battery is not oversized. I used a sealed Interstate unit: Y60-N24AL-B
• The carburetors came from Stan Smith at Rocky Point Cycle 937-376-9792

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Oil pump bearing cross-references

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The physical dimensions of the needle roller bearing (MG# 92252210) for the oil pump is as follows:

• ID: 10 mm
• OD: 22 mm
• Width: 20 mm

Here are various cross-references:

• FAG NKI 10/20
• IKO TAFI 102220
• INA NKI 10/20
• SKF NKI 10/20
• SKF (Old No.) NA 102220

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Owner's manuals

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NOTE: If you have trouble viewing PDF files inside your browser, try saving them to your computer (right-click the link, then choose the save option). Then, open each file directly in Adobe Acrobat Reader.

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Rear drive O-ring size

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The physical dimensions of the o-ring (MG# 90706584) for the rear drive are as follows:

• ID: 57 mm
• Width: 2.75 mm

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Rear drive seal sizes

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Large inner seal

The physical dimensions of this single lip seal (MG# 90407085) are as follows:

• ID: 70 mm
• OD: 85 mm
• Width: 8 mm

Small outer seal

The physical dimensions of this single lip seal (MG# 90403850) are as follows (Viton seals with serrated lips are recommended):

• ID: 38 mm
• OD: 50 mm
• Width: 7 mm

The physical dimensions of the seals for the rear drive are as follows:

• Large inner seal (MG# 90407085): 70 mm ID x 85 mm OD x 8 mm thick
• Small outer seal (MG# 90403850): 38 mm ID x 50 mm OD x 7 mm thick

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Rear wheel cush drive O-ring size

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The physical dimensions of the o-ring (MG# 90706490) that seals the cush drive to the rear wheel is as follows:

• 51 mm ID x 2.5 mm thick

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Spare parts catalogs

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Steering head bearing cross-references

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Thanks to Bob Greene for providing key starting information for these cross-references.

The physical dimensions of the tapered roller bearings (MG# 92249225) are as follows:

• ID: 25 mm
• OD: 52 mm
• Width: 16.25 mm

Here are various cross-references:

• Maryland Metric item no. 30205
• FAG 30205A
• RIV 01/02/7205
• SKF 30205J2
• SNR 30205
• STEYR 30205

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Swing arm bearing cross-references

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Thanks to Bob Greene provided key starting information for these cross-references.

The physical dimensions of the swing arm bearings (MG# 92249216) are as follows:

• ID: 17 mm
• OD: 40 mm
• Width: 12 mm

Here are a couple of cross-references:

• RIV 01/02/5010
• SKF 639215

The following physical dimensions are slightly thicker, but work just fine and are much easier to source than the original (thanks to Fred on the Yahoo! Loopframe_Guzzi news group for confirming the fitment).

• ID: 17 mm
• OD: 40 mm
• Width: 13.25 mm

Cross-references for the slightly thicker swing arm bearings:

• Maryland Metric item no. 30203
• FAG 30203A
• RIV 01/02/7203
• SKF (Eur.) 30203A
• SNR 30203
• STEYR 30203

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Swing arm bearing seal sizes

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The physical dimensions of the seals (MG# 90403040) for the swing arm pivots is as follows:

30 mm ID x 40 mm OD x 7 mm thick.

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Transmission bearing cross-references - 5 speeds

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All are of the standard ball bearing type except where otherwise noted; all are open (not shielded or sealed).

Note: I have visually verified all of the bearing sizes.

Input/clutch shaft

• Front of transmission (MG# 92218424):
  • 25 mm ID x 52 mm OD x 20.6 mm thick - this is a double row ball bearing
    • FAG 3205
    • FED 5205
    • ND 5205
    • New Departure 5205
    • RIV 3205 or 2AANOn25
    • SKF 5205
    • SKF (Eur.) 3205
    • STEYR 3205
• Rear of transmission (MG# 92256218):
  • 17 mm ID x 35 mm OD x 15 mm thick - this is a needle bearing
    • Durkopp 10-2762
    • RIV NAS 17
    • Torrington 10-2762
    • Timken 10-2762

Main/cluster shaft

• Front of transmission (MG# 92256218):
  • 17 mm ID x 35 mm OD x 15 mm thick - this is a needle bearing
    • Durkopp 10-2762
    • RIV NAS 17
    • Torrington 10-2762
    • Timken 10-2762
• Rear of transmission (MG# 92201417):
  • 17 mm ID x 17 mm OD x 14 mm thick
    • FAF 303K
    • FAG 6303
    • FED 1303
    • MRC 303-S
    • ND 3303
    • New Departure 3303
    • NH 303
    • RIV 4B or 6303
    • SKF 6303
    • STEYR 6303

Lay/output shaft

• Front of transmission (MG# 92234117):
  • 17 mm ID x 47 mm OD x 14 mm thick - this is a cylindrical roller bearing
    • FAG NF 303
    • HOFF R 317 L
    • RIV FN 303
    • SKF (Eur.) NF 303
    • STEYR NF 303
• Rear of transmission (MG# 92218424):
  • 25 mm ID x 52 mm OD x 20.6 mm thick - this is a double row ball bearing
    • FAG 3205
    • FED 5205
    • ND 5205
    • New Departure 5205
    • RIV 3205 or 2AANOn25
    • SKF 5205
    • SKF (Eur.) 3205
    • STEYR 3205

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Transmission bearing cross-references - I-Convert

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Throw out bearing

The physical dimensions of the throw out bearing (MG# 92204217) is as follows:

• ID: 17 mm
• OD: 40 mm
• Width: 12 mm

Here are various cross-references:

• FAF 203PP
• FAG 6203.2RSR
• FED 1203RR
• MRC 203-SZZ
• ND Z99503
• NH 203KK
• RIV ALN 17
• SKF 6203-2RS1
• STEYR 6203.2RS

Clutch assembly bearing

The physical dimensions of the bearing used in the clutch assembly (MG# 92201220) is as follows:

• ID: 20 mm
• OD: 47 mm
• Width: 14 mm

Here are various cross-references:

• FAF 204K
• FAG 6204
• FED 1204
• MRC 204-S
• ND 3204
• NH 204
• RIV 1A 20
• SKF 6204
• STEYR 6204

Input shaft (clutch shaft) bearing - front

The physical dimensions of the front bearing on the input shaft (clutch shaft) (MG# 92218421) is as follows:

• ID: 20 mm
• OD: 47 mm
• Width: 20.6 mm

Here are various cross-references:

• FAG 3204
• FED 5204
• RIV 2 AANOn20
• SKF 3204
• STEYR 3204

Input shaft (clutch shaft) bearing - rear

The physical dimensions of the rear bearing on the input shaft (clutch shaft) (MG# 92256218) is as follows:

• ID: 17 mm
• OD: 35 mm
• Width: 15 mm

Here are various cross-references:

• Durkopp 10-2762
• RIV NAS 17
• Torrington 10-2762
• Timken 10-2762

Main shaft bearing - front

The physical dimensions of the front bearing on the main shaft (MG# 92201420) is as follows:

• ID: 20 mm
• OD: 52 mm
• Width: 15 mm

Here are various cross-references:

• FAF 304K
• FAG 6304
• FED 1304
• MRC 304-S
• ND 3304
• NH 304
• RIV 5B
• SKF 6304
• STEYR 6304

Main shaft bearing - rear

The physical dimensions of the rear bearing on the main shaft (MG# 92256218) is as follows:

• ID: 17 mm
• OD: 35 mm
• Width: 15 mm

Here are various cross-references:

• Durkopp 10-2762
• RIV NAS 17
• Torrington 10-2762
• Timken 10-2762

Output shaft (layshaft) bearing - front

The physical dimensions of the front bearing on the output shaft (layshaft) (MG# 92201420) is as follows:

• ID: 20 mm
• OD: 52 mm
• Width: 15 mm

Here are various cross-references:

• FAF 304K
• FAG 6304
• FED 1304
• MRC 304-S
• ND 3304
• NH 304
• RIV 5B
• SKF 6304
• STEYR 6304

Output shaft (layshaft) bearing - rear

The physical dimensions of the rear bearing on the output shaft (layshaft) (MG# 92201425) is as follows:

• ID: 25 mm
• OD: 62 mm
• Width: 17 mm

Here are various cross-references:

• FAF 305K
• FAG 6305
• FED 1305
• MRC 305-S
• ND 3305
• NH 305
• RIV 6B
• SKF 6305
• STEYR 6305

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U-joint carrier bearing cross-references

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The physical dimensions of the sealed carrier bearing (MG# 92204230) are as follows:

• ID: 30 mm
• OD: 62 mm
• Width: 16 mm

Here are various cross-references:

• FAF 206PP
• FAG 6206.2RSR
• FED 1206RR
• MRC 206-SZZ
• ND Z99506
• NH 206KK
• RIV ALN 30
• SKF 6206-2RS1
• STEYR 6206.2RS

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Wheel bearing cross-references

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I-Convert mag wheels - Front

The physical dimensions of the front wheel bearings (sealed on both sides) are as follows:

• ID: 20 mm
• OD: 42 mm
• Width: 12 mm

Here are serveral cross-references:

• FAF 9104PP
• FAG 6004.2RSR
• MRC 104-KSZZ
• ND 993L04
• NH 6104KK
• RIV 10L20
• SKF 6004.2RS1
• STEYR 6004.2RS

I-Convert mag wheels - Rear

The physical dimensions of the rear wheel bearings (sealed on both sides) are as follows:

• ID: 20 mm
• OD: 47 mm
• Width: 14 mm

Here are serveral cross-references:

• FAF 204PP
• FAG 6204.2RSR
• FED 1204RR
• MRC 204-SZZ
• ND Z99504
• NH 204NN
• RIV ALN 20
• SKF 6204-2RS1
• STEYR 6204.2RS

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Workshop manuals

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